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  • 1
    Electronic Resource
    Electronic Resource
    The future of DNA-DNA hybridization studies (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 196-201 
    Details
    ISSN: 1432-1432
    Keywords: Human evolution ; Australian songbirds ; Convergent evolution ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This article draws on many vertebrate examples to assess the future of DNA-DNA hybridization studies. I first discuss whether applications of the method have reached the point of diminishing returns, or rather the start of a great leap forward, in our evolutionary understanding. Vertebrate groups whose relationships are especially likely to be illuminated include parrots, pigeons, bats, pinnipeds, mammalian carnivores, frogs, and rodents. There are at least two reasons why classifications based on DNA-DNA hybridization may prove to differ from classifications based on particular character, whether these be noncoding DNA sequences or protein sequences or anatomical characters. Because evolutionary relationships can now be deduced independently of anatomical characters, this should permit a renaissance in comparative anatomical studies of adaptation. The origin of major functional shifts from changes in a small fraction of the genome is illustrated by polar bears, sea otters, warblers, vultures, and especially by humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02099991
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  • 2
    Electronic Resource
    Electronic Resource
    Evolution of regulatory genes and patterns: Relationships to evolutionary rates and to metabolic functions (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 590-599 
    Details
    ISSN: 1432-1432
    Keywords: Evolution ; Gene regulation ; Drosophila ; Adaptation ; Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an effort to understand the forces shaping evolution of regulatory genes and patterns, we have compared data on interspecific differences in enzyme expression patterns among the rapidly evolving Hawaiian picture-winged Drosophila to similar data on the more conservative virilis species group. Divergence of regulatory patterns is significantly more common in the former group, but cause and effect are difficult to discern. Random fixation of regulatory variants in small populations and/or during speciation may be somewhat more likely than divergence driven by selection. Within the picture-winged group, we also have compared enzymes that fulfill different metabolic roles. There are highly significant differences between individual enzymes, but no obvious correlations to functional categories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00182745
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  • 3
    Electronic Resource
    Electronic Resource
    Growth of bacteria at 100°C and beyond (1981)
    Springer
    Archives of microbiology 129 (1981), S. 127-128 
    Details
    ISSN: 1432-072X
    Keywords: Continuous culture ; Adaptation ; Simulation of hot springs ; Boiling point ; Caldoactive bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacillus caldolyticus, a caldoactive bacterium originating from a hot spring at Yellowstone Park, was grown in a defined medium, whose composition resembled that of the pool water. Using a chemostat culture, which simulated the natural conditions, the organism could be adapted to grow at 100°C at a reasonable rate. Under increased pressure growth occurred also at 105° C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455347
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  • 4
    Electronic Resource
    Electronic Resource
    Properties of enzymes from bacteria grown in the 70–100°C range (1981)
    Springer
    Archives of microbiology 130 (1981), S. 159-164 
    Details
    ISSN: 1432-072X
    Keywords: Adaptation ; Boiling point ; Caldoactive enzymes ; Stabilization ; Thermostability ; Thermal characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In chemostat cultures of Bacillus caldolyticus, adaptation in a single step from 70–100°C was followed under aerobic and oxygen-limited conditions and was found to proceed more smoothly under the latter circumstances. Variations of the medium (e.g. yeast extract or silicate concentrations) showed that growth at 100°C is in all respects similar to that of cultures at moderate temperatures. Enzyme preparations derived from cultures at 5°C intervals between 70 and 100°C were used to determine the temperature range. For all nine enzymes tested, the optimum temperature was found to be 67°C; the latter was independent of the growth temperature. Differences were found, however, with respect to the maximum temperature of individual enzymes, and three groups, with maxima between 70 and 80°C, 80 and 90°C and 90 and 100°C can be distinguished. Again, there was no correlation with the growth temperature. Stability experiments also revealed that enzymes from the same organism can have different thermal properties: Some were found to be quite thermolabile (e.g. the pyruvate kinase), while others (e.g. hexokinase and glutamate-pyruvate transaminase) exhibited a high thermostability. These properties were not related to the growth temperature within the 70–100°C range, too. Six of the enzymes tested could be stabilized by their respective substrates, but the degree of protection varied for individual enzymes. Three enzymes (acetate kinase, glutamate dehydrogenase and myokinase) could not be stabilized by their substrates. Comparative experiments with the hexokinase suggested, that the thermal integrity of the enzymes is better protected within the cell as compared to the stability of the enzyme preparations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411071
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of photoperiodicity and light irradiance on phosphate-limited Oscillatoria agardhii in chemostat cultures (1985)
    Springer
    Archives of microbiology 142 (1985), S. 66-71 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Adaptation ; Photosynthesis ; Carbohydrate accumulation ; Relative growth rate ; [Light-phosphate] interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Oscillatoria agardhii was grown in continuous culture under various light conditions in order to study the interactions of light on phosphorus-limited growth. Under severe P-limiting (light-saturating) conditions, a low chlorophyll a and C-phycocyanin content was found. In addition, the light-harvesting capacity, reflected in the values of P max (maximum light-saturated oxygen production rate) and α (photosynthetic affinity), were low compared to light-limited cultures. Reduction of the light climate, either by reduction of the length of the photoperiod or light-intensity, resulted in an increase in light-harvesting capacity (higher pigment content, P m and α) during growth under P-limiting conditions. Light-induced changes in P max and α could be related to the relative growth rate, being the actual growth rate as a fraction of the growth rate which would be observed under light-limiting conditions. Under P-limiting conditions, reduction of the light-climate caused a reduction in dry weight of the culture. This decrease was mainly due to a decrease in carbohydrate content of the cells. Under all conditions tested, carbohydrates were found to accumulate during the light-period and to be consumed during the dark-period. Evaluation of carbohydrate consumption in the dark yielded a specific maintenance rate constant of 0.001 h-1. This observation leads to the conclusion that the specific maintenance rate constant is independent on the character of the growth rate limiting nutrient for O. agardhii.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409239
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  • 6
    Electronic Resource
    Electronic Resource
    Alterations of alkaline phosphatase activity during adaptation of Escherichia coli to phosphite and hypophosphite (1977)
    Springer
    Archives of microbiology 112 (1977), S. 103-107 
    Details
    ISSN: 1432-072X
    Keywords: Alkaline phosphatase ; Adaptation ; Derepression ; Repression ; Phosphite ; Hypophosphite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When Escherichia coli cells were grown in media containing either phosphite or hypophosphite as the sole source of phosphorus, they responded to this situation primarily in the same way as phosphatelimited cultures: The activity of alkaline phosphatase increased drastically, which under natural conditions would enable the cells to compklensatae for the shortage increased drastically, which under natural conditions would enable the cells to compensate for the shortage of phosphate. Subsequent transfers, however, resulted in a quite different response: While the phosphatase activity of phosphate-limited cells stays at a high derepressed level, its increase was followed by a gradual decline in organisms grown on phosphite or hypophosphite. After eight to ten transfers on these P-compounds, phosphatase activity was back to its initial, repressed, low level, indicating that the cells were fully adapted to these substrates. Adaptation to either PO 3 3- or PO 2 3- was completely abolished if the cells were again grown with PO 4 3- as P-source, whereafter the entire process of adaptation had to be repeated. The observed adaptation pattern, reflected by the alterations of phosphatase activity, was qualitatively equal with PO 3 3- and PO 2 3- , but quantitatively different, because the response to hypophosphite gave much higher values than the increase obtained with phosphite. Phosphite-adapted cells are not simultaneously adapted to hypophosphite, but their response to the latter was less intense than observed after direct transfers from PO 4 3- to PO 2 3- . Adaptation to hypophosphite, however, led simultaneously to phosphite adaptation, so that these cells can utilize both P-compounds as a substitute for phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446661
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  • 7
    Electronic Resource
    Electronic Resource
    Growth of Nitrobacter in the presence of organic matter (1976)
    Springer
    Archives of microbiology 108 (1976), S. 299-304 
    Details
    ISSN: 1432-072X
    Keywords: Nitrobacter ; Mixotrophic growth ; Cell-yield ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Culture filtrates of heterotrophic bacteria were tested for their stimulatory effect on nitrification of three strains of Nitrobacter. 2. Yeast extract-peptone solution, in which Pseudomonas fluorescens had grown, after removal of the cells was added to autotrophically growing cultures of Nitrobacter agilis; it caused a stimulated nitrite oxidation and growth of Nitrobacter agilis. 3. The degree of stimulation depended on: a) the proportion of the culture filtrate to the autotrophic medium; b) the composition of the complex medium in which Pseudomonas fluorescens had been grown; c) the time the heterotrophic bacterium had been grown in the complex medium. 4. The stimulatory effect was highest with Nitrobacter agilis, less with Nitrobacter winogradskyi and negligible with Nitrobacter K 4. 5. It was possible to adapt nitrifying cells of Nitrobacter agilis to higher concentrations of yeast extract and peptone. After the nitrite had been completely oxidized the cell-N still increased up to 30% before growth stopped.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454856
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  • 8
    Electronic Resource
    Electronic Resource
    Conversion of energy in halobacteria: ATP synthesis and phototaxis (1996)
    Springer
    Archives of microbiology 166 (1996), S. 1-11 
    Details
    ISSN: 1432-072X
    Keywords: Key words Archaea ; Halobacteria ; Energy ; transduction ; Retinal protein ; Proton gradient ; Nitrate ; reductase ; ATPase ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Halobacteria are aerobic chemo-organotroph archaea that grow optimally between pH 8 and 9 using a wide range of carbon sources. These archaea have developed alternative processes of energy provision for conditions of high cell densities and the reduced solubility of molecular oxygen in concentrated brines. The halobacteria can switch to anaerobic metabolism by using an alternative final acceptor in the respiratory chain or by fermentation, or alternatively, they can employ photophosphorylation. Light energy is converted by several retinal-containing membrane proteins that, in addition to generating a proton gradient across the cell membrane, also make phototaxis possible in order to approach optimal light conditions. The structural and functional features of ATP synthesis in archaea are discussed, and similarities to F-ATPases (functional aspects) or vacuolar ATPases (structural aspects) are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050349
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  • 9
    Electronic Resource
    Electronic Resource
    Adaptation by hot spring phototrophs to reduced light intensities (1977)
    Springer
    Archives of microbiology 113 (1977), S. 111-120 
    Details
    ISSN: 1432-072X
    Keywords: Adaptation ; Reduced light ; Chloroflexus ; Synechococcus ; Ecological studies ; Yellowstone ; National Park ; Hot springs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis was measured by the 14C method on natural as well as low light adapted populations of Chloroflexus (a photosynthetic bacterium) and Synechococcus (a blue-green alga) from hot springs in Yellowstone National Park (Wyoming U.S.A.), to test the ability of these phototrophs to photosynthesize at a variety of light intensities. The herbicide 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) was used to distinguish uptake of the blue-green alga from that of the photosynthetic bacterium, while measurements of chlorophyll a and bacterio-chlorophyll c served to quantitate the standing crops of these organisms. Natural populations of Synechococcus were found to be slightly inhibited by full sunlight intensities (summer values can surpass 90000 Lux), whereas the Chloroflexus populations were not. Populations of both phototrophs subjected to reduced light intensities through the use of neutral density filters were found to adapt to low light, and then become severely inhibited by high light intensities. Adaptation to various light regimes may be an important ecological phenomenon to the survival of these hot spring phototrophs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428590
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of sodium chloride on the plasma membrane of halotolerant Dunaliella primolecta: an electron spin resonance study (1982)
    Springer
    Archives of microbiology 131 (1982), S. 184-190 
    Details
    ISSN: 1432-072X
    Keywords: Dunaliella primolecta ; Malotolerant ; Adaptation ; Plasma membrane ; ESR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electron spin resonance spectroscopy was used to monitor the in vivo microviscosity of the plasma membrane and lipid extracts of the salt tolerant alga, Dunaliella primolecta. The fluidity of the plasma membrane decreased as the algae were adapted to and suspended in higher sodium chloride concentrations [2–24% (w/v)]. Both biochemical modification and a physical interaction between Na+ and lipids were implicated. When the microviscosity of the plasma membrane and that of lipid extracts were determined as a function of temperature, two or three lipid phase transformations were observed. There were always transformations at 9–14° C and 39–43° C. These were interpreted as the onset and completion of the lipid phase transition of at least a major lipid component of the membrane, possibly the entire membrane. These transformation temperatures were independent of the salt concentration to which the algae were adapted or suspended. This suggests that D. primolecta exists with some of its membrane in the solid-fluid mixed lipid state. With a NaCl concentration of 8% (w/v) or greater in the growth medium, a third transformation occurred around 20–22° C. It was the result of a lipid-lipid interaction and was not related to adaptation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405876
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  • 11
    Electronic Resource
    Electronic Resource
    Light-adaptation in the photophobic response by Stentor coeruleus (1987)
    Springer
    Archives of microbiology 147 (1987), S. 117-120 
    Details
    ISSN: 1432-072X
    Keywords: Adaptation ; Ciliate ; Stentor coeruleus ; Photophobic response ; Action spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of preillumination on photophobic response (light-adaptation) and recovery of the photophobic sensitivity in the dark (dark-adaptation) in Stentor coeruleus were examined. When the cells were preilluminated with white light of 7.80 W/m2 for 2 min, the fluence-rate response curve of photophobic response was shifted toward higher light intensities by half an order of magnitude compared to the one without preillumination. Preillumination with a higher light intensity resulted in a further shift of the fluencerate response curve. An action spectrum for light-adaptation showed a primary peak at 610 nm and secondary peaks at 540 and 480 nm which are almost identical to the peaks observed in the photophobic action spectrum. The light-adapted cells showed a recovery of their photophobic sensing ability following dark treatment. Dark-adaptation resulted in total recovery of photophobic sensing ability in 8 minutes for the most cases examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00415271
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  • 12
    Electronic Resource
    Electronic Resource
    The vhuU gene encoding a small subunit of a selenium-containing [NiFe]-hydrogenase in Methanococcus voltae appears to be essential for the cell (1998)
    Springer
    Archives of microbiology 170 (1998), S. 418-426 
    Details
    ISSN: 1432-072X
    Keywords: Key words Archaea ; Methanococcus voltae ; Deletion ; mutagenesis ; Adaptation ; Selenium deprivation ; [NiFe]-hydrogenases ; Gene replacement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We developed a general method for the site-specific deletion of gene sequences to obtain new selectable markers in the archaeon Methanococcus voltae. Using a deletion in the hisA gene, a vector was integrated into the chromosome by homologous recombination, thereby reconstituting histidine prototrophy. The vector contained the β-glucuronidase gene uidA of Escherichia coli as a reporter under the control of an M. voltae promoter that normally drives the expression of a selenium-free [NiFe]-hydrogenase after selenium deprivation. This construct has allowed us to check whether the selenium supply was sufficiently low to induce the transcription of the genes encoding the selenium-free hydrogenases. We tried to introduce a chromosomal deletion of the vhuU gene of the archaeon M. voltae by gene replacement and by keeping the cells under selenium deprivation. The gene vhuU encodes the very small, selenocysteine-containing subunit that is part of the primary reaction center of the Vhu hydrogenase. All transformants bearing the deletion also contained the vhuU wild-type gene. Therefore, the vhuU gene appears to be essential for the cell even under conditions that lead to the induction of the selenium-free homologue Vhc of the Vhu hydrogenase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050662
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  • 13
    Electronic Resource
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    Ultra-violet mutagenesis of Synechocystis sp. 6701: mutations in chromatic adaptation and phycobilisome assembly (1984)
    Springer
    Archives of microbiology 138 (1984), S. 237-243 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Synechocystis 6701 ; Phycobilisomes ; Ultra-violet ; Mutagenesis ; Assembly ; Chromatic ; Adaptation ; Rods ; Cores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutations affecting pigmentation of the cyanobacterium Synechocystis sp. 6701 were induced with ultraviolet light. Two mutants with phycobilisome structural changes were selected for structural studies. One mutant, UV08, was defective in chromatic adaptation and incorporated phycoerythrin into phycobilisomes in white or red light at a level typical of growth in green light. The other mutant, UV16, was defective in phycobilisome assembly: little phycocyanin was made and none was attached to the phycobilisome cores. The cores were completely free of any rod substructures and contained the major core peptides plus the 27,000 Mr linker peptide that attaches rods to the core. Micrographs of the core particles established their structural details. Phycoerythrin in UV 16 was assembled into rod structures that were not associated with core material or phycocyanin. The 30,500 Mr and 31,500 Mr linker peptides were present in the phycoerythrin rods with the 30,500 Mr protein as the major component. Phycobilisome assembly in vivo is discussed in light of this unusual mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402128
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  • 14
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    Photosensory transduction in the flagellated alga, Euglena gracilis (1983)
    Springer
    Archives of microbiology 134 (1983), S. 204-207 
    Details
    ISSN: 1432-072X
    Keywords: Photosensory ; Cations ; pH ; Flagellated ; Algae ; Adaptation ; Euglena gracilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Euglena were cultured under 3 W m-2 constant white light. In culture medium, cells show immediate and long lasting step-down photophobic responses and photoaccumulation behavior to blue light if dim red light-adapted for 30 min. However, if cells are suspended in buffered, saltcontaining solutions (adaptation buffers), strong step-down photobehavior and photoaccumulation responses are not observed for several hours. These behaviors gradually increase in strength to reach a maximum after 6–12 h; after which a stable response is maintained. The relative rates of appearance and the relative strengths of the responses are influenced by the concentrations of Ca2+ and K+, but not H+ or Na+ ions, in the adaptation buffers. Expression of the stepdown photobehavior thus requires that the cells adapt to the chemical environment in which they are suspended.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407758
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  • 15
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    Theoretical considerations on growth kinetics and physiological adaptation of nutrient-limited phytoplankton (1984)
    Springer
    Archives of microbiology 140 (1984), S. 96-100 
    Details
    ISSN: 1432-072X
    Keywords: Physiology ; Adaptation ; Growth ; Droop ; Monod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In many experimental ecological studies on phytoplankton species the growth response of an organism to the prevailing environmental conditions have been studied. Curves relating specific growth rate (μ) to the external nutrient concentration (S) have been constructed to compare nutrient-limited growth of different species under steady state conditions. Microorganisms adapt their physiology to a certain limitation in order to optimize growth. Therefore the shape of the μ/S curve is closely related to the way a micoorganism adapts its physiology. To see how physiological adaptation and growth rate are interconnected to each other, both can be related to the internal concentration of the growth-limiting nutrient. How the growth rate is related to the internal nutrient concentration is presented in a mathematical equation. Many phytoplankton species during growth under different nutrient limitations show a linear relationship between μ and the reciprocal value of the internal nutrient content (= Yield). This was originally observed by Droop. The model presented here gives a theoretical explanation of this phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409779
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  • 16
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    Thermoadaptation of enzymes in thermophilic and mesophilic cultures of Bacillus stearothermophilus and Bacillus caldotenax (1974)
    Springer
    Archives of microbiology 98 (1974), S. 275-287 
    Details
    ISSN: 1432-072X
    Keywords: Thermophilic bacteria ; B. stearothermophilus ; B. caldotenax ; Thermophilic (Thermostable) Enzymes ; Adaptation ; Thermoadaptation of Enzymes ; Thermoadaptation of Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Bacillus stearothermophilus was adapted to 37° C (mesophilic culture) and to 55° C (thermophilic culture) by cultivation via an intermediate temperature of 46° C. In the crude extract of the thermophilic bacterial cells the glucokinase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and isocitrate dehydrogenase are more thermostable than the corresponding enzymes in the crude extract of mesophilic cells. At the intermediate temperature of 46° C both types are probably formed. 2. 37° C-precultures of Bacillus caldotenax were further cultivated (in different samples) at 5° C intervals between 30° C and 70° C. It was shown that in 70° C-cells of the above mentioned enzymes more thermostable forms and in 37° C-cells more thermolabile forms are present. Furthermore, as demonstrated in the case of glucose-6-phosphate isomerase and isocitrate dehydrogenase, cells cultured in the temperature range between 30–50° C produced thermolabile enzyme variants (M-type), while cultures between 60–70° C produced thermostable variants (Th-type). At cultivation temperatures above 50° C a pronounced lag-period expressing the metabolic changes was found. In the lag-period, mesophilic enzymes are no longer present as early as 20 min after increasing the temperature (70° C), and synthesis of thermostable enzymes starts about 1 h before the beginning of growth. 3. Similar results were obtained with Bacillus caldotenax precultivated at 70° C and cultivated between 30° C and 70° C.
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    URL: http://dx.doi.org/10.1007/BF00425289
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  • 17
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    Can strains give adequate information for adaptive bone remodeling? (1984)
    Springer
    Calcified tissue international 36 (1984), S. S118 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Strain ; Remodeling ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary For bone to remodel adaptively, the cells responsible should follow some algorithm. Nine different loading situations and structures are discussed. It seems that either algorithm must be extremely complex, or cells in different structures must follow different algorithms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02406144
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  • 18
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    Quantitative model for the electric response of invertebrate and vertebrate photoreceptors (1977)
    Springer
    European biophysics journal 2 (1977), S. 333-336 
    Details
    ISSN: 1432-1017
    Keywords: Photoreceptor model ; Receptor potential ; Vertebrate ; Invertebrate ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We propose that the same mechanism which leads to light-adaptation in invertebrate photoreceptors is responsible for the excitation of the receptor potential in vertebrates. Several qualitative and quantitative features of the vertebrate receptor response support this hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537503
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  • 19
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    The correlation of the receptor potential with the light induced transient increase in intracellular calcium-concentration measured by absorption change of arsenazo III injected into Limulus ventral nerve photoreceptor cell (1980)
    Springer
    European biophysics journal 6 (1980), S. 191-208 
    Details
    ISSN: 1432-1017
    Keywords: Receptor potential ; Intracellular and extracellular calcium concentration ; Intensity dependence ; Adaptation ; Sensitivity control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The light-induced membrane voltage response (receptor potential, ReP) and the absorption change of the intracellularly injected calcium indicator arsenazo III (arsenazo response) were recorded simultaneously in Limulus ventral nerve photoreceptor cells. A double pulse technique was applied for stimulation. After pressure injection of the indicator into the cell absorption changes were measured at 646 nm to obtain a measure of the changes of the intracellular calcium ion concentration. 1. The size of the arsenazo response increases with increasing intensity of the light stimulus. The intensity dependence of the size of the arsenazo response δAmax shows almost no correlate with the peak amplitude of the ReP, but correlates rather well with the time integral of the ReP. 2. Decreasing light adaptation (caused by prolongation of the repetition time of the pulse pairs) leads to an increase in size of the arsenazo response. Also here δAmax correlates better with the time integral of the ReP than with its peak amplitude. 3. Lowering the calcium concentration in the superfusate (from 10 mmol/l to ca. 40 Μmol/l) causes after ca. 10 min a drastical diminution of the arsenazo response to values below the noise level, and a less marked reduction in size of the ReP. The falling phase of the ReP is slower. After return to normal calcium concentration the arsenazo response recovers partly in ca. 50 min, while the ReP recovers faster. The results show two opposite correlations between ReP and arsenazo response: Increase in size and duration of the ReP causes a greater transient increase of the intracellular calcium ion concentration. This in turn tends to reduce and shorten the ReP. Which effect dominates obviously depends on the conditions of the experiment: when the calcium concentration in the superfusate is reduced to ca. 40 Μmol/l a slow decrease of the ReP is accompanied by a small increase of the intracellular calcium ion concentration.
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    URL: http://dx.doi.org/10.1007/BF00537293
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  • 20
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    Dark adaptation processes in the amphibian rod (1977)
    Springer
    European biophysics journal 3 (1977), S. 171-173 
    Details
    ISSN: 1432-1017
    Keywords: Adaptation ; Frog ; Retina ; Rhodopsin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Rod dark adaptation in the amphibian retina appears to be due to three processes: 1. background adaptation, occurring immediately after the extinction of an adapting or bleaching light, 2. intermediate adaptation, that frequently lasts 30 min or more and 3. opsin adaptation, which in the isolated retina where regeneration of rhodopsin is insignificant, is observed as a permanent loss of sensitivity after the completion of intermediate adaptation. Intermediate adaptation is characterized by a linear relation between log threshold and the amount of “retinal” present, a similar relation is obtained between log threshold and the amount of rhodopsin bleached in opsin adaptation. These adaptation processes are discussed in terms of a model of the rod outer segment.
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    Adaptation properties of the ERG in the grasshopper, Romalea microptera (1981)
    Springer
    European biophysics journal 7 (1981), S. 205-208 
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    ISSN: 1432-1017
    Keywords: Grasshopper ; Electroretinogram ; Adaptation ; Spectral sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The grasshopper ERG displays a rapid recovery of responsivity following the onset of a background light. Although observed earlier in skate and frog, this phenomenon has not previously been seen in an invertebrate. Furthermore, a period of hyperresponsivity exists in early dark adaptation and resembles that found in skate and frog. Thus, recovery in the light and hyperresponsivity in the dark seem to be corollaries of each other. Finally, spectral sensitivity of the ERG is determined and two peaks are found: one at 510 nm and the other at 360 nm. The former appears to be a rhodopsin-mediated sensitivity but the latter does not and they are not clearly separated by chromatic adaptation.
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    URL: http://dx.doi.org/10.1007/BF00539180
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    Absorption of light by metarhodopsin modifies the effect of a conditioning light on the barnacle photoreceptor (1979)
    Springer
    European biophysics journal 5 (1979), S. 231-235 
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    ISSN: 1432-1017
    Keywords: Visual pigment ; Photoreceptor ; Metarhodopsin ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We show that the effect of an adapting light on the sensitivity of barnacle photoreceptors depends on the direction of net pigment transfer [rhodopsin (R) to metarhodopsin (M) or reverse] occasioned by the adapting light. For stimuli giving no net pigment transfer the state of the pigment appears irrelevant, R → R having the same effect as M → M. With respect to these, R → M gives enhanced facilitation and M → R depressed facilitation. This suggests a correlation with the prolonged depolarising after-potential (PDA) and the anti-PDA, which follow R → M and M → R stimuli respectively. These effects appear mainly in less sensitive cells and for higher amounts of conditioning light — but still well within the physiological range and well below the threshold for PDA and anti-PDA induction. The special interest of these results is that they appear to be interpretable only by assuming that absorption of light by metarhodopsin exerts an effect on the stimulus coincident response (LRP), the first demonstration of such an effect.
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    An analysis of rod outer segment adaptation based on a simple equivalent circuit (1978)
    Springer
    European biophysics journal 4 (1978), S. 115-128 
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    ISSN: 1432-1017
    Keywords: Adaptation ; Rod outer segment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract This model of rod outer segment adaptation is based on the hypothesis that transmitter substance released by bleached rhodopsin closes sodium channels in the outer segment plasma membrane, leading to hyperpolarization of the receptor. The outer segment adaptation processes of the model are associated with the transmitter release, the transmitter background concentration and the plasma membrane leakage. Changes in the three model parameters correspond to the three types of outer segment adaptation processes. According to the model the stimulus-response function is in every adaptational state U/U max −I/(I+I H ). The model predicts how each adaptation process affects I H and U max. Specifically, when the number of liberated transmitter molecules per isomerizing quantum decreases, the amplitude U max remains constant but I H increases. A short description of this model has been published in a paper reporting experimental results on background adaptation (HemilÄ, 1977).
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    The contribution of pigment transitions to sensitivity changes in the barnacle photoreceptor and the correlation with the prolonged depolarizing afterpotential (1982)
    Springer
    European biophysics journal 8 (1982), S. 161-172 
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    ISSN: 1432-1017
    Keywords: Photoreceptor ; Visual pigment ; Adaptation ; Facilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A conditioning light can cause a decrease (adaptation) or an increase (facilitation) in the sensitivity of barnacle photoreceptors, as measured by the amplitude of the late receptor potential (LRP). We show that a net transfer of visual pigment from the rhodopsin (R) to the metarhodopsin (M) state induces a large facilitation whereas the reverse transfer results in a much smaller facilitation or even an adaptation. These effects were not due to the response to the conditioning light but to the pigment reactions. When the conditioning light did not alter the pigment population (i.e., M → M, R → R) it was followed by an intermediate degree of facilitation. These conclusions are correct for cells which have relatively low sensitivity. In sensitive cells, all pigment transitions produce adaptation. LRP facilitation and the prolonged depolarizing afterpotential (PDA) show several common characteristics with respect to pigment transitions: 1.Their magnitude increases with the amount of pigment transferred from R to M. 2. Both are depressed by the M → R transition. 3. Their production is impeded by the M → R transition. 4. The PDA itself is facilitated by the R → M transition and this facilitation decays with a time course comparable to that of LRP facilitation. These results suggest that there may be an underlying process common to LRP facilitation and PDA.
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    Sensitivity changes of photoreceptor cells of Hirudo medicinalis caused by changes in extracellular calcium concentration (1982)
    Springer
    European biophysics journal 8 (1982), S. 173-187 
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    ISSN: 1432-1017
    Keywords: Leech photoreceptors ; Extracellular calcium ; Excitation ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Extracellular recordings from the vacoule of photoreceptor cells of Hirudo medicinalis L. were performed using microelectrodes. The cells were adapted by white light flashes given at constant intervals (20 s). Response height versus relative intensity curves obtained from the same cell in physiological saline (PS) and in bathing solutions of either a) lowered calcium contents (2 ΜM/1 or less) or b) raised calcium contents (15 mM/1) were compared. The cells' adaptation state in PS was operationally defined by the ratio Q=h A /h S where h A is the response height evoked by the adapting flashes, and h S is the corresponding saturation response height. Sensitivity changes were measured by the half saturation intensity shift. Lowering extracellular calcium resulted in: 1. The response height increased and the shape of the response became more rounded and prolonged. 2. The total resistance between the vacuole and outside decreased from 8.2±1.4 MΩ (n=6) in PS to 4.6±0.4 MΩ (n=5). The resistance was independent of the cells' adaptation state. 3. A change of the cells' sensitivity occured either in direction to light adaptation or in direction to dark adaptation. It depended functionally on the ratio Q: a) if Q was less or equal to about 0.6 the cells' sensitivity increased. b) if Q was greater than 0.6 the cells' sensitivity diminished. Raising extracellular calcium decreased the sensitivity of all cells tested independent of their adaptation states in PS. The results can be interpreted under the assumptions that 1. the sensitivity of leech photoreceptor cells is inversely proportional to the intracellular free calcium concentration and Z. intracellular calcium can interact with extracellular calcium in relatively dark adapted cells whereas in relatively light adapted cells the raise of intracellular free calcium is mainly effected by a release from intracellular stores. It is assumed that a Q value of about 0.6 separates relatively light adapted cells from relatively dark adapted cells.
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    Phosphorylation of rhodopsin as a possible mechanism of adaptation (1977)
    Springer
    European biophysics journal 3 (1977), S. 175-180 
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    ISSN: 1432-1017
    Keywords: Rodopsin ; Phosphorylation ; Adaptation ; Retina ; Cyclic nucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Light-induced phosphorylation of rhodopsin has been extensively studied by a number of investigators from a biochemical point of view. However, little is known about the physiological function of this reaction. The slow rates measured for phosphorylation and dephosphorylation suggest that it may be involved in visual adaptation rather than in excitation. This paper presents biochemical data obtained from phosphorylation experiments in isolated photoreceptor membranes as well as in the more physiological system of whole retinas and living animals. An attempt is made to compare the phosphorylation reaction with visual adaptation hypotheses taken from the electrophysiological literature. Finally, effects of cyclic nucleotide metabolism on the sensitivity of photoreceptors are presented and discussed.
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    Calcium ion, a putative intracellular messenger for light-adaptation in Limulus ventral photoreceptors (1977)
    Springer
    European biophysics journal 3 (1977), S. 141-143 
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    ISSN: 1432-1017
    Keywords: Calcium ; Limulus ; Photoreceptors ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Calcium ion fulfills several criteria for identifying an intracellular messenger for light-adaptation in Limulus photoreceptors. Direct injection of Ca++ mimicks two aspects of light-adaptation; sequestration of intracellular calcium tends to prevent light-adaptation; and light induces an increase in intracellular Ca++ as demonstrated by two independent techniques.
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    An improvement in Pichia stipitis fermentation of acid-hydrolysed hemicellulose achieved by overliming (calcium hydroxide treatment) and strain adaptation (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 281-283 
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    ISSN: 1573-0972
    Keywords: Adaptation ; fermentation ; hemicellulose ; hydrolysate ; overliming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The fermentability of a corn cob, acid-hydrolysed hemicellulose by Pichia stipitis was considerably improved by pre-treatment with Ca(OH)2. The total sugars utilized and ethanol yield for the untreated hydrolysate were 18% and 0.21 g/g, respectively, compared with 82% and 0.32 g/g respectively for the treated material. Adaptation of the yeast to the hydrolysate resulted in a significantly higher fermentation rate with over 90% of the initial total sugars being utilized and an ethanol yield and maximum ethanol concentration of 0.41 g/g and 13.3 g/l, respectively.
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    Continuous anaerobic phenol degradation using an adapted mixed culture (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 409-411 
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    ISSN: 1573-0972
    Keywords: Adaptation ; anaerobic ; packed bed ; phenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A mixed culture derived from cow dung and sewage sludge and adapted to phenol was used for anaerobic phenol degradation. The phenol degradation rate depended on the period of adaptation of the mixed culture to phenol. In the continuous process, a higher degradation rate (2500 mg.1-1 d-1) and better reactor stability was achieved with a granular activated-carbon-packed bed reactor than with a stirred tank reactor.
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    Bacteria tolerant to organic solvents (1998)
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    Extremophiles 2 (1998), S. 229-238 
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    ISSN: 1433-4909
    Keywords: Key words Solvent-tolerant bacteria ; Adaptation ; Resistance ; Toxicity ; Log P ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The toxic effects that organic solvents have on whole cells is an important drawback in the application of these solvents in environmental biotechnology and in the production of fine chemicals by whole-cell biotransformations. Hydrophobic organic solvents, such as toluene, are toxic for living organisms because they accumulate in and disrupt cell membranes. The toxicity of a compound correlates with the logarithm of its partition coefficient with octanol and water (log P ow). Substances with a log P ow value between 1 and 5 are, in general, toxic for whole cells. However, in recent years different bacterial strains have been isolated and characterized that can adapt to the presence of organic solvents. These strains grow in the presence of a second phase of solvents previously believed to be lethal. Different mechanisms contributing to the solvent tolerance of these strains have been found. Alterations in the composition of the cytoplasmic and outer membrane have been described. These adaptations suppress the effects of the solvents on the membrane stability or limit the rate of diffusion into the membrane. Furthermore, changes in the rate of the biosynthesis of the phospholipids were reported to accelerate repair processes. In addition to these adaptation mechanisms compensating the toxic effect of the organic solvents, mechanisms do exist that actively decrease the amount of the toxic solvent in the cells. An efflux system actively decreasing the amount of solvents in the cell has been described recently. We review here the current knowledge about exceptional strains that can grow in the presence of toxic solvents and the mechanisms responsible for their survival.
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    Bacillus sp. WW3-SN6, a novel facultatively alkaliphilic bacterium isolated from the washwaters of edible olives (2000)
    Springer
    Extremophiles 4 (2000), S. 201-208 
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    ISSN: 1433-4909
    Keywords: Key words Olive wastes ; Bacillus ; Alkaliphile ; Growth characteristics ; Lipid composition ; Phylogeny ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel Gram-positive facultatively alkaliphilic, sporulating, rod-shaped bacterium, designated as WW3-SN6, has been isolated from the alkaline washwaters derived from the preparation of edible olives. The bacterium is nonmotile, and flagella are not observed. It is oxidase positive and catalase negative. The facultative alkaliphile grows from pH 7.0 to 10.5, with a broad optimum from pH 8.0 to 9.0. It could grow in up to 15% (w/v) NaCl, and over the temperature range from 4° to 37°C, with an optimum between 27° and 32°C: therefore, it is both halotolerant and psychrotolerant. The bacterium is sensitive to a range of β-lactam, sulfonamide, and aminoglycoside antibiotics, but resistant to trimethoprim. The range of amino acids, sugars, and polyols utilized as growth substrates indicates that this alkaliphile is a heterotrophic bacterium. d(+)-glucose, d(+)-glucose-6-phosphate, d(+)-cellobiose, starch, or sucrose are the substrates best utilized. The major membrane lipids are phosphatidylglycerol and diphosphatidylglycerol, with smaller amounts of phosphatidylethanolamine and an unknown phospholipid. During growth at high pH, the proportion of phosphatidylglycerol is increased relative to phosphatidylethanolamine. The fatty acyl components in the membrane phospholipids are mainly branched chain, with 13-methyl tetradecanoic and 12-methyl tetradecanoic acids as the predominant components. The G + C content of the genomic DNA is 41.1 ± 1.0 mol%. The results of 16S ribosomal RNA sequence analysis place this alkaliphilic bacterium in a cluster, together with an unnamed alkaliphilic Bacillus species (98.2% similarity).
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    Regulation of sex-specific feeding behavior in fiddler crabs: physiological properties of chemoreceptor neurons in claws and legs of males and females (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 513-526 
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    ISSN: 1432-1351
    Keywords: Adaptation ; Chemosensation ; Crustacea ; Disadaptation ; Sexual dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This study examined properties of chemoreceptor neurons in the claws and legs of the fiddler crabs Uca pugilator and U. pugnax. The primary goal was to establish the neural basis of previously observed greater female sensitivity to feeding stimulants, and secondarily to compare physiological properties of chemoreceptor neurons in these semi-terrestrial crustaceans with those of fully aquatic forms. Sensitivity of chemoreceptor neurons in claws and legs is sex-specific; individual neurons of females respond to lower stimulus concentrations than male chemoreceptor neurons, and equivalent concentrations elicit greater spiking in female vs male chemoreceptor neurons. Thus, the population of chemoreceptor neurons in females expresses lower thresholds and greater average sensitivity than in males. Greater sensitivity of claw neurons explains observations indicating that females continue to feed at food levels too low to stimulate males. Sensitivity differences in leg neurons of males vs females have no clear behavioral correlate, but suggest that females can orient to more dilute stimuli than males. Chemoreceptor neurons of fiddler crabs have low sensitivities and slow rates of adaptation compared to other crustaceans. Also, neurons in claws adapt less slowly than neurons in legs, which may reflect subtle differences in the chemical stimulus environment experienced by claws vs legs.
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    Resolution of pheromone pulses in receptor cells of Antheraea polyphemus at different temperatures (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 301-310 
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    ISSN: 1432-1351
    Keywords: Pheromone receptor cells ; Single sensillum recording ; Temperature dependence ; Nerve-impulse response ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ability of pheromone receptor cells of male Antheraea polyphemus (Saturniidae) to resolve stimulus pulses was determined at different temperatures (8°, 18°, 28°C). The cells were stimulated by repeated 20-ms puffs of the pheromone components (E, Z)-6, 11-hexadecadienyl acetate and (E, Z)-6,11-hexadecadienal. At higher temperatures, higher frequencies of stimulus pulses were resolved by the nerve-impulse response: about 1.25 pulses per second at 8°C, 2.5 pulses/s at 18°C and 5 pulses/s at 28°C. The decreased ability of receptor cells to resolve stimulus pulses at low temperatures may reduce the male moth's chance of reaching the pheromone source. The peak nerve-impulse frequency increased whereas the duration of nerve-impulse responses to single stimulus pulses decreased at higher temperatures. At a given temperature and stimulus intensity the peak nerveimpulse frequency decreased with shorter intervals between the stimulus pulses, but the duration of the responses remained almost constant. The time needed for recovery from adaptation caused by a single stimulus pulse was longer at lower temperatures. The aldehyde receptor cell recovered more quickly than the acetate cell. At low stimulus concentration, the resolution ability of the acetate cell was strongly decreased, whereas in the aldehyde cell it was only slightly impaired.
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    An informational approach to sensory adaptation (1991)
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    Journal of comparative physiology 168 (1991), S. 151-157 
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    ISSN: 1432-1351
    Keywords: Adaptation ; Information ; Unifying theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Concepts from information theory can enhance our understanding of perceptual processes by providing a unified picture of the process of perception. A single equation is shown to embrace adaptation phenomena, stimulus-response relations, and differential thresholds. Sensory adaptation is regarded as representing a gain in information by the receptor. It is calculated that for constant stimuli in the form of step inputs, insects and arachnids obtain approximately the same amount of information per stimulus from their respective environments as do human beings.
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    Light-induced changes in extracellular calcium concentration in the compound eye of Calliphora, Locusta and Apis (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 573-581 
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    ISSN: 1432-1351
    Keywords: Insect retina ; Extracellular calcium ; Species differences ; Photoreceptor ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ion-selective microelectrodes inserted into the compound eyes of Calliphora, Locusta and Apis were used to monitor the changes in extracellular concentration of Ca2+ (Cao) brought about by a 1-min exposure to white light (maximal luminous intensity ca. 103 cd/m2). In the blowfly retina such stimulation causes a decrease in Cao. At high light intensities the Cao signal is phasic, falling over about 6 s to a transient light-induced minimum (ΔCao= -6.2% ± 0.4%, n = 20, SE) and then rising to an approximately stable plateau (-3.3% ± 0.6%). In migratory locusts the light-induced minimum corresponds to a ΔCao of -13.8% ± 1.6% (n = 10), and at the plateau the Cao decrease is-13.2% ± 1.5%. In honey-bees Cao at first decreases only slightly, by -2.6% ± 1.0% (n = 10); by the end of the 1-min stimulus the extracellular concentration averages 33.6% ± 14.6% above the dark level. The results suggest a relationship between the position of the characteristic curve of the photoreceptor in the dark-adapted state, the occurrence of quantum bumps, and light-induced increases or decreases in Cao. Therefore the species differences might be interpreted as a consequence of differences in the intracellular dark concentration of Ca2+.
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    Location and dynamic properties of the spike generator in an insect mechanosensory neuron (1996)
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    Journal of comparative physiology 179 (1996), S. 235-243 
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    ISSN: 1432-1351
    Keywords: Adaptation ; Insect ; Dendrite ; Encoding ; Mechanoreceptor ; Power law
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1.The cereal bristle hairs of the cockroach, Periplaneta americana, are each innervated by one mechanosensory cell and 1–5 chemosensory cells. In transepithelial recordings, chemo- and mechanosensory spikes could be discriminated from each other by their relative amplitude. 2. When current steps were applied via the sensory hair, trains of impulses were triggered whatever the polarity of the current. 3. All responses adapted to the current, but the time course of adaptation was fitted by a power law for outward currents and an exponential law for inward currents. 4. During application of outward currents, the spikes showed a negative initial phase on which a small positive component was superimposed; strong polarizations produced purely negative spikes. More classical spikes with a positive initial phase were induced by inward currents. 5. The present work supports the hypothesis of a direct excitability of the apical dendrite in cereal bristle mechanoreceptors and confirms previous results suggesting that spikes are normally triggered within that region during mechanical stimulations. It is also established, for the first time, that adaptation to currents may be different in the apical dendrite and in more basal regions of the same mechanosensory neuron.
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    Temporal coding of pheromone pulses and trains in Manduca sexta (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 505-512 
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    ISSN: 1432-1351
    Keywords: anduca sexta ; Olfaction ; Pheromones ; Temporal coding ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We investigated the ability of pheromone-sensitive olfactory receptors of male Manduca sexta to respond to 20-ms pulses of bombykal, the major component of the conspecific pheromonal blend. Isolated pulses of bombykal elicited a burst of activity which decreased exponentially with a time constant of 160–250 ms. Trains of pulses delivered at increasing frequencies (0.5–10 Hz) elicited temporally modulated responses at up to 3 Hz. Concentration of the stimulus (1, 10, 100 ng per odor source) had a marginal effect on the temporal resolution of the receptors. Within a train, the responses to individual pulses remained constant, except for 10-Hz trains (short-term adaptation). A dose-dependent decline of responsiveness was observed during experiments (long-term adaptation). Although individual neurons may not respond faithfully to each pulse of a train, the population of receptors sampled in this study appears to be capable of encoding the onset of odor pulses at frequencies of up to at least 3 Hz.
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    Time course of color induction in the honeybee (1995)
    Springer
    Journal of comparative physiology 177 (1995), S. 207-217 
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    ISSN: 1432-1351
    Keywords: Honeybee ; Color vision ; Behavior ; Adaptation ; Color induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Color induction in the honeybee is investigated in color discrimination experiments. An individual bee walks in a dark arena and is trained to a self-luminant stimulus presented from below. In the dual-choice tests the dark background is replaced by a colored induction stimulus. Choice behavior is recorded by TV camera and analyzed by computer. Successive color induction is separated from simultaneous induction by analysis of the walking paths. Only successive color induction occurs. Simultaneous effects are not observed. That is a stimulus acts as a color inducing stimulus only when the bee crosses this stimulus. Thus, the color perceived by a given eye region is found to be dependent on the viewing history, but not on the stimuli presented simultaneously on neighboring parts of the retina. Color induction in the honeybee described in terms of selective sensitivity decrease (adaptation) does not explain all behavioral effects induced by the stimulus. The time course of successive color induction is calculated from the exposure times to the induction stimulus and from the choice behavior. The data suggest that color induction is complete after a few seconds. Photoreceptor adaptation is sufficient to explain the observed time course.
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    Chemosensory responses of Tetrahymena thermophila to CB2, a 24-amino-acid fragment of lysozyme (1999)
    Springer
    Journal of comparative physiology 184 (1999), S. 529-534 
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    ISSN: 1432-1351
    Keywords: Key words Chemorepellent ; Chemosensory transduction ; Receptor potential ; Adaptation ; Receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract While lysozyme is a depolarizing chemorepellent in Tetrahymena, the entire lysozyme molecule is not necessary to activate the lysozyme receptor. Reduced lysozyme was cut into three fragments by cyanogen bromide cleavage and the fragments (CB1, CB2 and CB3) were separated by HPLC. Behavioral bioassays showed that the carboxy-terminal 24-amino-acid fragment, which we call CB2, is 100 times more active than intact lysozyme as a chemorepellent. CB2 appears to activate the same receptor as lysozyme because behavioral cross-adaptation is seen between these two compounds and an antibody generated to the purified lysozyme receptor blocks responses to both lysozyme and CB2. This is further supported by the observation that neomycin, which is a competitive inhibitor of lysozyme binding, also inhibits CB2 responses. This inhibition may be due to the fact that neomycin is highly positively charged (+5 at pH 7.0) and CB2 has a net charge of +4 at pH 7.0. Intracellular electrophysiological recordings documented that CB2 elicits a transient, depolarizing receptor potential that is similar to the lysozyme-induced depolarizations except they are much smaller. CB2 is a more potent and specific ligand for use in studies of the lysozyme receptor of Tetrahymena.
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    Morphological correlates of pyramidal cell adaptation rate in the electrosensory lateral line lobe of weakly electric fish (1991)
    Springer
    Journal of comparative physiology 168 (1991), S. 393-407 
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    ISSN: 1432-1351
    Keywords: Electroreception ; Descending control ; Adaptation ; Pyramidal cells ; Weakly electric fish ; Sensory processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Extracellular HRP injections into the nucleus praeeminentialis dorsalis (NPd) ofApteronotus leptorhynchus retrogradely labeled a population of elec trosensory lateral line lobe (ELL) efferent cells, deep basilar pyramidal cells, that differ morphologically from the previously described basilar and nonbasilar pyramidal cells. These neurons are found deep in the ELL cellular layers; they have small cell bodies and very short sparsely branching apical dendritic trees. The previously described basilar and nonbasilar pyramidal cells are larger, have extensive apical dendrites and are found more superficially. 2. Axon terminals of the deep basilar pyramidal cells were recorded from in the NPd and labeled with lucifer yellow. These NPd afferents have high, regular spontaneous firing rates, and respond tonically to changes in electric organ discharge amplitude. 3. Deep basilar pyramidal cell bodies were recorded from and labeled in the ELL, and these showed the same physiological responses as did the NPd afferent fibers. 4. In addition, basilar pyramidal cells were found which had spontaneous activity patterns and adaptation characteristics intermediate to those typical of the superficial basilar pyramidal cells and the deep basilar pyramidal cells. The size of the pyramidal cells' apical dendritic trees and the placement of their somata within the dorsoventral extent of the ELL cellular layers are highly correlated with the neurons' physiological properties.
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    Three modes of spatiotemporal preprocessing by eyes (1993)
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    Journal of comparative physiology 172 (1993), S. 583-591 
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    ISSN: 1432-1351
    Keywords: Natural images ; Spatiotemporal filtering ; Adaptation ; Eye design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. Optimal spatiotemporal filters for early vision were computed as a function of signal-to-noise ratio (SNR) and α, a parameter defined as the ratio of the width of the probability distribution of velocities as perceived by the naturally behaving animal, and the characteristic velocity of the photoreceptors (the velocity required to move across a receptor's receptive field in a receptor's integration time). Animals that move slowly, on average, compared with the characteristic velocity of their photoreceptors have α ≪ 1, animals that move fast have α ≫ 1. 2. For α ≪ 1, the temporal part of the optimal filter adapts more to different SNRs (light levels) than the spatial part, leading to large adjustments in temporal resolving power and strong self-inhibition at high SNR, but little lateral inhibition. 3. For α ≫ 1, the spatial part of the filter adapts more strongly than the temporal part, leading to strong lateral inhibition at high SNR, and little self-inhibition. 4. For α ≈ 1, both spatial and temporal properties change about equally much when varying SNR. 5. Varying the width of the angular sensitivity of the photoreceptors shows that for every combination of α and SNR there is an optimal width. Visual systems with large α need wider angular sensitivities, in particular at low SNR, in order to reach the information maximum than visual systems with small α.
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    A quantitative model of successive color induction in the honeybee (1995)
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    Journal of comparative physiology 177 (1995), S. 219-234 
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    ISSN: 1432-1351
    Keywords: Color vision ; Honeybee ; Behavior ; Adaptation ; Lateral filtering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Intensity discrimination experiments are performed with individual walking honeybees trained to color stimuli (UV, blue and green) of constant intensity. The choice behavior to stimuli of identical wavelength spectrum but different intensities is tested. A graded choice behavior is found. The training intensity is chosen with the highest probability in most cases. Phototaxis as well as brightness discrimination can be excluded. The choice behavior is explained exclusively by discrimination of chromaticness (hue and saturation) according to the Bezold-Brücke shift. The bees adapt to the chromatic stimuli during their choices. From the behavioral data, it is concluded that in adaptation, adjustment in photoreceptor sensitivity in one receptor also affects the sensitivity of the other receptors (“co-adaptation”). The linear adaptation model corresponding to the von Kries Coefficient Law used up to now to describe adaptation to white light in the honeybee does not describe this type of adaptation. A quantitative model of adaptation to chromatic stimuli extending the linear adaptation model is developed. The most reasonable mechanism of co-adaptation is optical coupling by lateral filtering. Other mechanisms such as electrical coupling are unlikely, since their effects on color vision would lead to effects inconsistent with Graßmann's Laws.
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    Temporal analysis of adaptation in moth (Trichoplusia ni) pheromone receptor neurons (1992)
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    Journal of comparative physiology 170 (1992), S. 691-700 
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    ISSN: 1432-1351
    Keywords: Adaptation ; Temporal pattern ; Olfaction ; Insect ; Pheromone ; Receptor neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The temporal pattern of response in chemoreceptor neurons reflects both the temporal distribution of stimuli and the timing of signal transduction, action potential generation and propagation. Here we analyze the temporal characteristics of the responses elicited in pheromone receptor neurons by computer-controlled rectangular pulses of odorant. Extracellular recordings from the HS sensilla trichodea on the antenna of male Trichoplusia ni reveal the activity of two neurons: the “A” neuron, which responds to the major component of the female pheromone blend, (Z)7-dodecenyl acetate and the “B” neuron, which responds to (Z)7-dodecenol. “B” neurons were divided into two classes (HR, LR), based on the magnitude and temporal pattern of their response to (Z)7-dodecenol. Most “A” and HR “B” neurons responded to rectangular pulses of various durations (0.1–40 s) with an initial phasic burst (∼100 ms), followed by a slowly declining tonic component. At moderate and elevated pheromone doses, prolonged stimulation resulted in significant reductions in the tonic response levels (adaptation); stimuli of increasing duration effected greater adaptation. Most LR “B” neurons lacked a phasic response component and showed virtually no adaptation with prolonged stimulation. Pheromone receptor neurons may differ in both their spectral and temporal response properties which may provide the animal with additional sensory information for blend discrimination and spatial orientation in complex natural pheromone plumes. The potential functional value of adaptation in the moth pheromone communication system is discussed.
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    Altered mechanoreceptor response in Drosophila bang-sensitive mutants (1994)
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    Journal of comparative physiology 175 (1994), S. 267-278 
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    ISSN: 1432-1351
    Keywords: Drosophila ; Bang sensitivity ; Mechanotransduction ; Adaptation ; Sensory coding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bang-sensitive mutants of Drosophila melano gaster (bas 1, bssMW1, eas2, tko25t) display seizure followed by paralysis when subjected to mechanical shock. However, no physiological or biochemical defect has been found to be common to all of these mutants. In order to observe the effects of bang-sensitive mutations upon an identified neuron, and to study the nature of mechanically induced paralysis, we examined the response of a mechanosensory neuron in these mutants. In each single mutant and the double mutant bas 1 bssMW1, the frequency of action potentials in response to a bristle displacement was reduced. This is the first demonstration of a physiological defect common to several of the bang-sensitive mutations. Adaptation of spike frequency, cumulative adaptation to repeated stimulation (fatigue) and the time course of recovery from adaptation were also examined. Recovery from adaptation to a conditioning stimulus was examined in two mutants (bas 1 and bss MW1), and initial recovery from adaptation was greater in both mutants. Quantification of receptor potentials was complicated by variability inherent in extracellular recording conditions, but examination of the waveform and range of amplitudes did not indicate clear mutant defects. Therefore the differences observed in the spike response may be due to an alteration of the transfer from receptor potentials to action potential production. DNA sequence analysis of tko and eas has indicated that they encode apparently unrelated biochemical products. Our results suggest that these biochemical lesions lead to a common physiological defect in mechanoreceptors. Although this defect does not provide a straightforward explanation for bang sensitivity, the altered cellular process may lead to bang sensitivity through its action in different parts of the nervous system.
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    Song recognition in the grasshopper Chorthippus biguttulus is not impaired by shortening song signals: implications for neuronal encoding (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 729-735 
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    ISSN: 1432-1351
    Keywords: Key words Grasshoppers ; Acoustic communication ; Neuronal encoding ; Adaptation ; Neuronal reliability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The communication signals in many grasshopper species are composed of multiple repetitions of highly stereotyped subunits, and thus provide redundancy. In a behavioural paradigm, we tested the ability of males of the grasshopper Chorthippus biguttulus to recognize shortened versions of the communication signals of conspecific females. Males reliably responded to a three-subunits signal (250 ms), i.e. to a signal of less than a quarter of the natural duration. This performance is remarkable in view of the substantial adaptation and the variability present in the spiking responses of auditory interneurones. These behavioural results will impose constraints for investigating possible encoding mechanisms used by the grasshoppers' auditory system.
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    Development of sweating ability in winter- and summer-born Friesian calves aged 1 to 6 weeks (1989)
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    International journal of biometeorology 33 (1989), S. 246-250 
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    ISSN: 1432-1254
    Keywords: Sweating in calves ; Age and heat tolerance ; Sweating, age effects ; Sweating, seasonal effects ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Sweating rate, rectal and skin temperatures and respiration rate were measured at weekly intervals from 7 days of age (for 4 weeks in Experiment 1; 6 weeks in Experiment 2) in winter- and summer-born Friesian calves exposed to a temperature of 39°C dry bulb and 32°C wet bulb in a climate chamber. Four calves were studied in each season in both experiments. In Experiment 1, ambient temperatures were from 3° to 9°C higher in early summer than in late winter. During each 39°C exposure, sweating rate increased from basal levels of 40–90 to plateau levels of 120–300 g/m2 per h after 90–120 min. The increase in sweating rate with age was most pronounced in winter-born calves, but summer-born calves had higher values at 1 week of age (167±52.4 vs 94.4±30.1 g/m2 per h). Seasonal differences in ambient temperature were greater in Experiment 2 (11° to 17°C). In this case summer-born calves had higher sweating rates at each age (plateau values of 220–320 g/m2 per h), and showed a more rapid increase in sweating rate during each 39°C exposure than winter-born calves (plateau values of 100–250 g/m2 per h). The results demonstrate major changes in sweating competence during the first 4–6 weeks of life in Friesian calves, a quite pronounced effect of season (ambient temperature) on the levels of sweating achieved, and indicate that low sweating rates in newborn calves are a contributing factor in deaths due to hyperthermia in semi-arid grazing areas.
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    Adaptive locomotion to periodic perturbation. Adaptation mechanism with coupling of oscillator and link dynamics (1999)
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    Artificial life and robotics 3 (1999), S. 97-101 
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    ISSN: 1614-7456
    Keywords: Quadrupedal locomotion ; Gait pattern ; Adaptation ; Periodic perturbation ; Coupled oscillators ; Limb dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Quadrupeds can acquire new gait patterns with respect to environmental changes. Yanagihara et al. have demonstrated this adaptability by experiments on a decerebrate cat. These experiments indicate that quadrupeds gradually adapt to their environment by repeating locomotion in a steady environment, and that the acquired gait pattern is persistently memorized after the locomotion. Our research aims at formulating a mathematical model of these cats' behavior and constructing a quadrupedal walking robot to realize such adaptive behavior. To date, we have proposed a mathematical description of adaptation at the level of gait pattern generation using neural oscillators. In this paper, we extend it to take into account limb dynamics. We study how to design the interaction of the oscillator and limb dynamics.
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    Influence of environmental factors on the development of the valve in diatoms (1979)
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    Protoplasma 99 (1979), S. 99-115 
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    ISSN: 1615-6102
    Keywords: Adaptation ; Diatoms ; Environment ; Resting-spores ; Sexual reproduction ; Valve formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The species-specific form and structure of the diatom shell is variable within a given genetical reaction-norm, depending on the dynamic interrelation between cell and environment. The appearing modifications—based on quantitative disarrangement of construction-units as well as on a change in size and outline—can be understood as the morphological expression of a changed metabolism which has become necessary for adaption to adverse conditions. The diatoms react very sensitively, especially to the salinity factor, whereby actually two alternatives of adaption occur: a vegetative, in building resting spores (f.i., Navicula cuspidata) and a generative (f.i., Anomoeoneis sphaerophora, Surirella peisonis). Teratologies have been found in totally unbalanced surroundings (especially under conditions of ion unbalance), where the usually symmetrical forms have lost the coordination of the construction-units to each other (f.i., Surirella peisonis). They supply good criteria in clarifying the problems concerning pattern development.
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    Comparative leaf morphology of young sporophytes of rheophyticOsmunda lancea and drylandO. japonica (1993)
    Springer
    Journal of plant research 106 (1993), S. 37-45 
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    ISSN: 1618-0860
    Keywords: Adaptation ; Leaf morphology ; Ontogeny ; Osmunda lancea ; Rheophyte ; Young sporophytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field and morphological observations were made of the young sporophytes of rheophyticOsmunda lancea and its related drylandO. japonica, and the rheophyte's adaptation in the early sporophytic stages was discussed. Mature plants ofO. lancea andO. japonica do not occur in dryland and rheophytic habitats, respectively, but their very young sporophytes rarely grow there. The young sporophytes ofO. lancea differ considerably from those ofO. japonica in having the relatively short petioles with thin-walled epidermal cells, early lamina partition, cuneate leaf- and pinna-base, oblique (not horizontal) lamina disposition, a fine network of spongy tissue in the 4th and older leaves, and dense epicuticular wax deposits on leaf epidermis. They seem to relate to the flexibility of petioles and the toughness and flood-tolerance of blades, and make the young sporophytes adapted to the rheophytic habitat.Osmunda japonica lacking those characteristics disappears from the rheophytic habitat during the early ontogenetic stages.
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    Effect of adaptation to high-altitude hypoxia in early ontogeny on higher nervous activity (1976)
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    Bulletin of experimental biology and medicine 82 (1976), S. 1119-1121 
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    ISSN: 1573-8221
    Keywords: Adaptation ; hypoxia ; conditioned reflexes
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    Topics: Biology , Medicine
    Notes: Abstract Newborn male and female Wistar rats were adapted to hypoxia in a pressure chamber. Adaptation began at an “altitude” of 1000 m for 1 h daily, after which the duration and intensity of exposure were gradually increased so that, starting from the 17th day, the animals were adapted to an altitude of 5000 m for 5 h on 5 days a week. After adaptation for two months, a conditioned active avoidance reflex was produced in the animals. In the adapted males a tendency was observed for the reflex to be formed more rapidly and for it to be preserved to a much greater degree than in the control animals. In females adapted to hypoxia under similar conditions no changes were observed in the formation and preservation of the reflex.
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    Ubiquitin gene expression: response to environmental changes (1991)
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    Current genetics 20 (1991), S. 17-23 
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    ISSN: 1432-0983
    Keywords: Ubiquitin ; Regulation ; Adaptation ; Transcripts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It has previously been shown that the yeast ubiquitin genes UBI1, 2 and 3 are strongly expressed during the log-phase of batch culture growth, whereas the UBI4 gene is weakly expressed. We found that heat shock, treatment with DNA-damaging agents, starvation, and the feeding of starved cells all transiently induced UBI4. These results suggest that UBI4 is induced whenever a change in culture conditions dictates a dramatic shift in cellular metabolism, and that UBI4 expression returns to lower levels once cellular metabolism has adapted to the new conditions. In contrast, all of the treatments tested, except starvation, transiently repressed the UBI1, 2 and 3 genes. Although starvation also repressed UBI1, 2 and 3 its effect was not transient, and expression only recovered upon the addition of fresh media. These results, together with others presented here, suggest that high levels of UBI1, 2 and 3 expression are dependant upon ongoing cell growth, and that treatments which slow or stop growth repress their expression.
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    Adaptation and major chromosomal changes in populations of Saccharomyces cerevisiae (1992)
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    Current genetics 22 (1992), S. 13-19 
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    ISSN: 1432-0983
    Keywords: Chromosome length variants ; Adaptation ; Yeast ; Continuous culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thirteen independent populations of Saccharomyces cerevisiae (nine haploid and four diploid) were maintained in continuous culture for up to approximately 1000 generations, with growth limited by the concentration of organic phosphates in medium buffered at pH 6. Analysis of clones isolated from these populations showed that a number (17) of large-scale chromosomallength variants and rearrangements were present in the populations at their termination. Nine of the 16 yeast chromosomes were involved in such changes. Few of the changes could be explained by copy-number increases in the structural loci for acid phosphatase. Several considerations concerning the nature and frequency of the chromosome-length variants observed lead us to conclude that they are selectively advantageous.
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    Darwinian adaptation, population genetics and the streetcar theory of evolution (1996)
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    Journal of mathematical biology 34 (1996), S. 511-532 
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    ISSN: 1432-1416
    Keywords: Adaptation ; Optimality ; Nash equilibrium ; ESS ; N-locus genetics ; Epistasis ; Long-term evolution ; Rationality paradox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract This paper investigates the problem of how to conceive a robust theory of phenotypic adaptation in non-trivial models of evolutionary biology. A particular effort is made to develop a foundation of this theory in the context ofn-locus population genetics. Therefore, the evolution of phenotypic traits is considered that are coded for by more than one gene. The potential for epistatic gene interactions is not a priori excluded. Furthermore, emphasis is laid on the intricacies of frequency-dependent selection. It is first discussed how strongly the scope for phenotypic adaptation is restricted by the complex nature of ‘reproduction mechanics’ in sexually reproducing diploid populations. This discussion shows that one can easily lose the traces of Darwinsm inn-locus models of population genetics. In order to retrieve these traces, the outline of a new theory is given that I call ‘streetcar theory of evolution’. This theory is based on the same models that geneticists have used in order to demonstrate substantial problems with the ‘adaptationist programme’. However, these models are now analyzed differently by including thoughts about the evolutionary removal of genetic constraints. This requires consideration of a sufficiently wide range of potential mutant alleles and careful examination of what to consider as a stable state of the evolutionary process. A particular notion of stability is introduced in order to describe population states that are phenotypically stable against the effects of all mutant alleles that are to be expected in the long-run. Surprisingly, a long-term stable state can be characterized at the phenotypic level as a fitness maximum, a Nash equilibrium or an ESS. The paper presents these mathematical results and discusses — at unusual length for a mathematical journal — their fundamental role in our current understanding of evolution.
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    Seasonal variation in the photoperiodic responses of a pea aphid population: evidence for long-distance movements between populations (1989)
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    Oecologia 81 (1989), S. 160-165 
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    ISSN: 1432-1939
    Keywords: Acyrthosiphon pisum ; Migration ; Adaptation ; Photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The purpose of the study was to quantify long distance movements in populations of pea aphid, Acyrthosiphon pisum (Harris), by estimating origins and distances travelled by immigrants into a southern Manitoba population. A strong relationship was demonstrated between latitude of origin and photoperiods at which pea aphid populations are stimulated to produce the diapause stage (Smith 1987). Therefore, the approach was to use photoperiodic response as a physiological marker to identify the source of immigrant aphids. The responses of 89 clones from Glenlea, Manitoba (49°38′N), sampled 5 times over 2 seasons, were measured. One sample of clones collected the first season had photoperiodic responses similar to those of a population about 300 km to the south, and significantly different from clones collected in spring of the same year at the same site. Weather analysis corroberates that the migrants were probably carried into Manitoba on a southerly flow of air during the previous 24 to 36 h.
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    Adaptive variation in structure and function of kidneys of speciating subterranean mole rats (1989)
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    Oecologia 79 (1989), S. 366-371 
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    ISSN: 1432-1939
    Keywords: Adaptation ; Speciation ; Urine ; Kidney ; Spalax ehrenbergi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report on kidney structure and function in subterranean mammals of four chromosomal species (2n=52, 54, 58 and 60) belonging to the Spalax ehrenbergi superspecies, in relation to their speciation and adaptive radiation from mesic (2n=52) to xeric (2n=60) environments in Israel. Structural variables measured involved: (1) Relative Medullary Thickness, (RMT); (2) Relative Kidney Weight. (RKW); and (3) Percentage of Kidney out of Body Weight (PKW). Functional variables involved: (i) Urine Solid Concentration, (USC); and (ii) Urine Osmotic Concentration (UOC). The results for chromosomal species 2n=52, 54, 58 and 60 indicated nonsignificant increase southward for RMT, but displayed significant increase along the same transect for RKW, PKW, and USC. The UOC was significantly lower in mesic 2n=52 as compared to the other three species when experimental animals were fed in the laboratory on regular carrot food. However, protein stress food (soybean) and salt stress of 0.45 mol NaCl, caused significant, three and a half fold increase of UOC in 2n=52, 54 and 58; but four and a half fold increase in 2n=60, significantly higher than in the other three species. We conclude that both structurally and functionally, the kidneys differentiated adaptively during the Pleistocene evolution of S. ehrenbergi in Israel, in accordance with aridity stress and halophyte food resources towards the desert. Nevertheless, Spalax generally shows clear upper limits in kidney structural and functional capacities, preventing it from colonizing the true desert, south of the 100 mm isohyete.
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    Geographic variation in embryonic development time and stage of diapause in a grasshopper (1994)
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    Oecologia 97 (1994), S. 179-185 
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    ISSN: 1432-1939
    Keywords: Diapause ; Development ; Grasshopper ; Adaptation ; Geographic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryonic development times and the stage at which embryonic diapause occurs varied dramatically among 23 populations of the Melanoplus sanguinipes/ devastator species complex in California, USA. Grasshoppers were collected from a wide range of latitudes (32°57N to 41°20N) and altitudes (10m to 3031 m), spanning much of the variation in climatic conditions experienced by these insects in California. When reared in a “common garden” in the laboratory, total embryonic development times were positively correlated to the mean annual temperature of the habitat from which the grasshoppers were collected (varying from about 19 days to 32 days when reared at 27°C). These grasshoppers overwinter as diapausing eggs and the proportion of embryonic development completed prior to diapause was significantly higher in populations collected from cool habitats (〉70%) than in populations collected from warm environments (〈26%). The length of pre-diapause development time is determined by the stage of embryonic development at which diapause occurs, and varies considerably among populations of these grasshoppers; grasshoppers from warmer environments tend to diapause at very early stages of embryogenesis, while grasshoppers from cooler environments diapause at very late stages. The combined effect of variation in embryonic development times and variation in the stage at which diapause occurs results in a dramatic reduction in the time needed to hatch in the spring; populations from warm environments required up to 20 days (at 27°C) to hatch while populations from cool environments required as few as 5 days to complete embryonic development prior to hatching. Egg size also varied significantly among populations, but tended to be larger in populations with shorter embryonic development times. Significant family effects were observed for development time and stage of diapause, suggesting significant heritabilities for these traits, although maternal effects may also contribute to family level variation. We interpret these findings to support the hypothesis that embryonic development time and the stage of embryonic diapause have evolved as adaptations to prevailing season lengths in the study populations.
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    Analysis of the rye chromosome constitution and the amount of telomeric heterochromatin in the widely and narrowly adapted hexaploid triticales (1981)
    Springer
    Theoretical and applied genetics 60 (1981), S. 145-149 
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    ISSN: 1432-2242
    Keywords: Triticale ; Rye ; Hexaploids ; Adaptation ; Chromosomal substitutions ; Modified chromosomes ; Telomeric heterochromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Investigations were made on the rye chromosome constitution and on the presence of telomeric heterochromatin in rye chromosomes of the 26 most widely and 24 most narrowly adapted triticale strains. Among widely adapted lines, 22 (85%) had a complete rye genome and four triticales only had chromosomal R-D genome substitutions. Twenty-three (96%) of the 24 most narrowly adapted triticales had substitutions between the chromosomes of the R and D genomes. The most widely adapted triticales accumulated fewer modified rye chromosomes in comparison to narrowly adapted lines. They had from one to three rye chromosomes with heterochromatic deletions: 46% of widely adapted lines had two modified rye chromosomes; 34% had three modified rye chromosomes, and 19% had a single modified rye chromosome. In widely adapted strains, the 1R, 4R, 5R and 6R modified chromosomes were observed; they were present in 80%, 73%, 50% and 11% of the cases, respectively. The most narrowly adapted triticales had from two to four modified rye chromosomes: 58% of the strains had three modified rye chromosomes; 29% had four modified rye chromosomes and 12% had two modified rye chromosomes. The modified 4R and 5R chromosomes were present in all of these lines. The 1R (modified), 6R (modified) and 7R (modified) were found in 83%, 25% and 16%, respectively, of the narrowly adapted strains. Results support the previous observations (Pilch 1980b) that a wide adaptation of hexaploid triticales is associated with the presence of the full potential of rye genome, and that it is independent of the amount of telomeric heterochromatin possessed by rye chromosomes.
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    Behavioural evolution in the cabbage butterfly (Pieris rapae) (1987)
    Springer
    Oecologia 72 (1987), S. 69-76 
    Details
    ISSN: 1432-1939
    Keywords: Cabbage butterfly ; Pieris rapae ; Evolution ; Adaptation ; Colonisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Australian and U.K. Pieris rapae differ markedly in their oviposition behaviour; U.K. females produce a more aggregated egg distribution, and lay their eggs more quickly, than do Australian females. The adaptive reason for this divergence probably lies in the relative costs of increased flight time (more costly in the U.K.) and increased local crowding (more costly in Australia). There is also a strong relationship between juvenile developmental rate (at constant temperature) and oviposition behaviour, but the form of this relationship differed between the two populations. The adaptive reasons for the link between developmental rate and behaviour is not clear. It may be that this link represents the tip of the iceberg; i.e. that physiological, developmental, and behabioral characters all co-vary in ways and for reasons that we do not yet understand.
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    URL: http://dx.doi.org/10.1007/BF00385047
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    Comparative ecophysiology of Encelia farinosa and Encelia frutescens (1988)
    Springer
    Oecologia 76 (1988), S. 553-561 
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    ISSN: 1432-1939
    Keywords: Adaptation ; Carbon isotope ratio ; Leaf conductance ; Water-use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Encelia farinosa and Encelia frutescens are drought-decidous shrubs whose distributions overlap throughout much of the Sonoran Desert. During hot and dry periods, leaves of E. farinosa utilize increased leaf reflectance to reduce leaf temperature, whereas leaves of E. frutescens have substantially higher leaf conductances and rely on increased transpirational cooling to reduce leaf temperature. E. farinosa is common on the dry slope microhabitats, whereas E. frutescens occurs only in wash microhabitats where greater soil moisture is available to provide the water necessary for transpirational cooling. E. farinosa tends not to persist in wash microhabitats because of its greater susceptibility to flashfloods. The consequences and significance of increased leaf reflectance versus increased transpirational cooling to leaf temperature regulation are discussed.
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    URL: http://dx.doi.org/10.1007/BF00397869
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    Adaptive energy metabolism in four chromosomal species of subterranean mole rats (1988)
    Springer
    Oecologia 77 (1988), S. 533-536 
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    ISSN: 1432-1939
    Keywords: Energetics ; Speciation ; Adaptation ; Spalax ehrenbergi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gross energy intake and apparent dry matter digestibility of animals fed carrots ad lib in the laboratory, were measured in the four chromosomal species of the Spalax ehrenbergi superspecies in Israel. Gross energy intake of 132.8 and 155.9 kJ/day was measured for the 2n=52 and 2n=58 chromosomal “mesic” species, while in the 2n=54 and 2n=60 chromosomal “xeric” species it measured only 80.3 and 75.0 kJ/day, respectively. Dry matter digestibility ranged between 92.3 and 95.6% in thefour chromosomal species. The differences in gross energy intake between the “mesic” and “xeric” species, appeared to reflect adaptive energy metabolism variation associated with geographic variation in climate, habitat productivity, and food availability.
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    URL: http://dx.doi.org/10.1007/BF00377270
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    Plasticity or fixed adaptive traits? Strategies for predation avoidance in Rana arvalis tadpoles (1998)
    Springer
    Oecologia 117 (1998), S. 119-126 
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    ISSN: 1432-1939
    Keywords: Key words Amphibians ; Predation ; Plasticity ; Adaptation ; Life history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tadpoles of Rana arvalis originating from seven island populations were tested for responses to non-lethal predator presence. In general, tadpole growth was reduced and the relative tail depth was increased at predator presence. There was no effect of predator presence on the predicted size at metamorphosis. The differentiation rate, translating as length of the larval period, was lower at predator presence, but this seems to be merely an effect of the reduced growth. Although populations differed with respect to growth, relative tail length, relative tail depth, differentiation rate and predicted size at metamorphosis, no obvious differences were found in their responses to predator presence. Data on predator occurrences in the source ponds show that tadpoles originating from ponds with a high predation pressure have a higher differentiation rate, i.e. they will metamorphose at an earlier date than those from “safe” ponds (if raised under the same conditions). Moreover, they are also predicted to metamorphose at a smaller size, which is in accordance with theoretical models. Despite the fact that populations differed in growth, no correlation was found between growth and predation risk in the source ponds.
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    Biogeographical gradients in galling species richness (1988)
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    Oecologia 76 (1988), S. 161-167 
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    ISSN: 1432-1939
    Keywords: Adaptation ; Altitudinal gradients ; Herbivores ; Insect galls ; Species richness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Five hypotheses were invoked to account for variation in galling species number per location on plants of different structural complexity, namely herbs, shrubs, and trees, both in Brazil and USA. The hypotheses were: 1) the altitudinal/latitudinal gradient hypothesis; 2) the harsh environment hypothesis; 3) the plant species richness hypothesis; 4) the host plant area hypothesis; 5) the plant structural complexity hypothesis. The altitudinal and the harsh environment hypotheses were correlated and supported with sample data in both localities, with increasing gall species number as altitude/latitude declined and as sites became hotter and drier. The two hypotheses were separated by studying riparian sites and dry hillside sites at the same elevation in Arizona. Galling species frequency was higher in dry sites than in riparian sites, supporting the harsh environment hypothesis. Of the five hypotheses tested only the harsh environment hypothesis predicted that galling insect species number should vary in response to environmental variables such as moisture and temperature. Temperate shrubs supported more galling species than did other plant types, both in dry and mesic sites. The overall difference between galling species richness for tropical and temperate latitudes was not statistically significant. Free-feeding insect herbivore species exhibited the opposite pattern of species richness to gallers, being more speciose in riparian sites. The present study corroborates the hypothesis that the gall forming habit is an adaptation to harsh or stressful environments, and we describe for the first time broad scale geographical patterns in galling insect species richness.
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    Are development and growth of pea aphids, Acyrthosiphon pisum, in North America adapted to local temperatures? (1987)
    Springer
    Oecologia 72 (1987), S. 170-177 
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    ISSN: 1432-1939
    Keywords: Developmental rate ; Adult weight ; Adaptation ; Temperature ; Acyrthosiphon pisum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Developmental rate and adult weight were studied at constant temperatures from 9.8 to 27.9°C for 18 clones from each of five populations of the pea aphid, Acyrthosiphon pisum (Harris), from locations between 39 and 53°N latitude in central North America. The response of developmental rate to temperature for each clone was accurately described by a three parameter non-linear equation. Adult weight usually decreased with increasing rearing temperature, but the shape of the response to temperature varied among clones. Variation in the developmental parameters was greater among clones within populations than among populations. No consistent trends were observed in the developmental parameters or adult weights either with latitude or the long term average temperatures at the locations. We conclude that previously reported geographic variation in the developmental threshold of this species, which was attributed to local adaptation, occurred either because the clones tested were not representative of the populations or because rearing methods differed among studies. The results are discussed in relation to the hypothesis that life history traits which are temperature sensitive are adapted to local thermal environments.
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    URL: http://dx.doi.org/10.1007/BF00379263
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    Life history patterns in female moose (Alces alces): the relationship between age, body size, fecundity and environmental conditions (1996)
    Springer
    Oecologia 106 (1996), S. 212-220 
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    ISSN: 1432-1939
    Keywords: Fecundity ; Body size ; Climate ; Survival ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I examined the relationship between age, body size and fecundity in 833 female moose (Alces alces) from 14 populations in Sweden sampled during 1989–1992. Data on population density, food availability and climatic conditions were also collected for each population. Age and body mass were both significantly positively related to fecundity, measured as ovulation rate, among female moose. The relationship between the probability of ovulation and body mass was dependent on age with (1) a higher body mass needed in younger females for attaining a given fecundity, and (2) body mass having a stronger effect on fecundity in yearling (1.5 year) than in older (≥2.5 year) females. Thus, a 40 kg increase in yearling body mass resulted in a 42% increase in the probability of ovulation as compared to a 6% increase in older females. The lower reproductive effort per unit body mass, and the relatively stronger association between fecundity and body mass in young female moose compared to older ones, is likely to primarily represent a mechanism that trades off early maturation against further growth, indicating a higher cost of reproduction in young animals. In addition to age and body mass, population identity explained a significant amount of the individual variation in fecundity, showing that the relationship between body mass and fecundity was variable among populations. This variation was in turn related to the environment, in terms of climatic conditions forcing female moose living in relatively harsh/more seasonal climatic conditions to attain a 22% higher body mass to achive the same probability of multiple ovulation (twinning) as females living in climatically milder/less seasonal environments. The results suggests that the lower fecundity per unit body mass in female moose living in climatically harsh/more seasonal environments may be an adaptive response to lower rates of juvenile survival, compared to females experiencing relatively milder/less seasonal climatic conditions.
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    Characteristics of Encelia species differing in leaf reflectance and transpiration rate under common garden conditions (1990)
    Springer
    Oecologia 82 (1990), S. 484-489 
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    ISSN: 1432-1939
    Keywords: Adaptation ; Leaf pubescence ; Leaf reflectance ; Desert ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The performance of coastal and desert species of Encelia (Asteraceae) were evaluated through common garden growth observations. The obectives of the study were to evaluate the roles of leaf features, thought to be of adaptive value (increased leaf reflectance and/or transpirational cooling), on plant growth in the hot, arid, desert garden versus their impact on growth under cooler, relatively more moist coastal garden conditions. E. californica native to the coast of southern California and E. farinosa, and E. frutescens, interior desert species, were grown in common gardens at coastal (Irvine, California) and interior (Phoenix, Arizona) sites under both irrigated and natural conditions. Although all species survived in both gardens during the two and a half year study period, there were large differences in their sizes. In the desert garden, leaf conductance and leaf water potential were both lower than at the coastal site. E. californica shrubs were leafless much of the time under natural conditions in the desert garden and had the smallest size there as well. Under natural conditions, E. farinosa, with its reflective leaf surface, was able to maintain lower leaf temperatures and attained a large size than the other two species in the desert garden. The green-leaved species (E. californica and E. frutescens) were not able to maintain leaves into the drought periods in the desert garden, with the exception of the irrigated E. frutescens which did maintain its leaf area if provided with supplemental watering to maintain transpirational leaf cooling. In the coastal garden, all species survived and there were few clear differences in the physiological characteristics among the three species. E. californica, the coastal native, attained a larger size in the coastal garden when compared with either of the two desert species.
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    Information about previous phosphate fluctuations is stored via an adaptive response of the high-affinity phosphate uptake system of the cyanobacterium Anacystis nidulans (1995)
    Springer
    Planta 197 (1995), S. 147-155 
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    ISSN: 1432-2048
    Keywords: Adaptation ; Anacystis ; Cyanobacterium ; Information storage ; Phosphate uptake system ; Threshold concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The high-affinity uptake system of phosphatelimited cyanobacterium Anacystis nidulans [Synechococcus leopoliensis (Raciborski) Komarek] is characterized by a threshold value below which uptake cannot occur. Here it is shown that, if phosphate-limited cyanobacteria are challenged with a short pulse of high phosphate concentration that appreciably exceeds this threshold value, the uptake system undergoes an adaptive response, leading to the attainment of new kinetic properties and a new threshold value. These new properties are maintained for several hours after the pulse. A notable characteristic of this new state is a wide linear dependence of the uptake rate on the external phosphate potential that is a function of the driving force of the uptake process. According to theoretical arguments it is shown that this “linear operation mode” can be explained by the simultaneous operation of several uptake systems with different, staggered threshold values and kinetic properties. Moreover, the new linear uptake properties, in turn, reflect the prehistory of phosphate supply experienced by the population. The consequences of this result with regard to environmental fluctuations of the phosphate concentration in lakes are discussed.
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    The area under the function: an index for selecting desirable genotypes (1993)
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    Theoretical and applied genetics 87 (1993), S. 409-415 
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    ISSN: 1432-2242
    Keywords: Genotype x environment interaction ; Adaptation ; Stability ; Desirability index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The linear regression approach has been widely used for selecting high-yielding and stable genotypes targeted to several environments. The genotype mean yield and the regression coefficient of a genotype's performance on an index of environmental productivity are the two main stability parameters. Using both can often complicate the breeder's decision when comparing high-yielding, less-stable genotypes with low-yielding, stable genotypes. This study proposes to combine the mean yield and regression coefficient into a unified desirability index (D i). Thus, D i is defined as the area under the linear regression function divided by the difference between the two extreme environmental indexes. D i is equal to the mean of the i th genotype across all environments plus its slope multiplied by the mean of the environmental indexes of the two extreme environments (symmetry). Desirable genotypes are those with a large D i. For symmetric trials the desirability index depends largely on the mean yield of the genotype and for asymmetric trials the slope has an important influence on the desirability index. The use of D i was illustrated by a 20-environments maize yield trial and a 25-environments wheat yield trial. Three maize genotypes out of nine showed values of D i 's that were significantly larger than a hypothetical, stable genotype. These were considered desirable, even though two of them had slopes significantly greater than 1.0. The results obtained from ranking wheat genotypes on mean yield differ from a ranking based on D i .
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    Adaptation of sorghum: characterisation of genotypic flowering responses to temperature and photoperiod (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 900-911 
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    ISSN: 1432-2242
    Keywords: Key words Sorghum bicolor ; Flowering ; Temperature ; Photoperiod ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop grown in a wide range of tropical and temperate environments. This study was conducted to characterise the photothermal flowering responses of sorghum genotypes and to examine relationships between photothermal characteristics and environment of origin in order to better understand the phenological basis of adaptation to environment in sorghum. Twenty-four germplasm accessions and one hybrid from 24 major sorghum-growing areas were grown in a wide range of environments varying in temperature and photoperiod in India, Kenya and Mali between 1992 and 1995. Times from sowing to flowering (f) were recorded, and the responsiveness of 1/f to temperature and photoperiod was quantified using photothermal models. Times from sowing to flowering were accurately predicted in a wide range of environments using a multiplicative rate photothermal model. Significant variation in the minimum time to flower (Fm) and photoperiod sensitivity (critical photoperiod, Pc, and photoperiod-sensitivity slope, Ps) was observed among the genotypes; in contrast there was little variation in base temperature (Tb). Adaptation of sorghum to the diverse environments in which it is grown was largely determined by photoperiod sensitivity and minimum time to flower; photoperiod sensitivity determines broad adaptation to latitude (daylength), while variation in the minimum time to flower determines specific adaptation within smaller ranges of latitude, e.g. within the humid and sub-humid tropics.
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    URL: http://dx.doi.org/10.1007/s001220051311
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    The vertical foliage distributions of six understory tree species in a Chamaecyparis obtusa Endl. forest (1988)
    Springer
    Trees 2 (1988), S. 143-149 
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    ISSN: 1432-2285
    Keywords: Adaptation ; Leaf distribution ; Mono-layer ; Multi-layer ; Understory tree species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationships between the amounts of foliage and heights of trees were studied for the dominant understory tree species, including three evergreen and three deciduous species, in a secondary forest of Chamaecyparis obtusa Endl. The relationships showed two phases: leaf increasing and stationary phases. In the leaf-increasing phase, the height growth allowed these species to expand the canopy by increasing the number of leaves. In the stationary phase, the number of leaves was relatively constant number irrespective of tree height from 160 to 400 cm. The number of leaves in the stationary phase represents the maximum number of leaves that can be supported by trees under shady conditions. From the analyses of vertical distributions of leaves in six species, mono- and multi-layer foliage distributions were detected. Two evergreen species, Eurya japonica and Cleyera japonica, showed multi-layer foliage distributions, whereas three deciduous species, Lyonia ovalifolia, Rhododendron reticulatum and Vaccinium hirtum, and one evergreen species, Pieris japonica, showed mono-layer foliage distributions. The relationships between the weights of non-photosynthetic and photosynthetic organs of the six species were examined. The proportion of non-photosynthetic organs increased with tree height. The understory species attained the stationary phase and were maintained by minimizing their investment in non-photosynthetic organs, i.e. their height growth was arrested by the shady conditions under the crown trees.
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    Nuclear DNA amount, growth, and yield parameters in maize (1994)
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    Theoretical and applied genetics 88 (1994), S. 557-560 
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    ISSN: 1432-2242
    Keywords: Zea mays L. ; Genome size ; Adaptation ; Nucleotype ; Agronomic performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extensive nuclear DNA content variation has been observed inZea mays. Of particular interest is the effect of this variation on the agronomic potential of maize. In the present study, yield and growth data were collected on 12 southwestern US maize open-pollinated populations. These populations, originally cultivated by the Indians of the southwestern US for both human and animal consumption and adapted to various altitudes, were grown in replicated plots at the University of Illinois Agronomy-Plant Pathology South Farm. All growth and yield parameters were found to be negatively correlated with nuclear DNA amount. The negative correlations of nuclear DNA amount and growth parameters were more pronounced at 60 days after planting (DAP) than 30 DAP. Agronomically-important yield parameters, such as ear or seed weight and seed number per plant, also exhibited a significant negative correlations with nuclear DNA amount. These correlations demonstrate how the nucleotype may exhibit a high degree of influence on the agronomic phenotype. Although the results presented here represent only three replications at one location in 1 year, the observations noted suggest that nucleotype plays an integral role in determining the agronomic performance of maize. Further studies are needed to fully document this role.
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    Genetic analysis of adaptation differences between highland and lowland tropical maize using molecular markers (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1106-1119 
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    ISSN: 1432-2242
    Keywords: Key words Maize ; Adaptation ; Tropical ; Highland and lowland ; QTL mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Molecular-marker loci were used to investigate the adaptation differences between highland and lowland tropical maize. An F2 population from the cross of two inbred lines independently derived from highland and lowland maize germplasm was developed, and extracted F3:4 lines were phenotype in replicated field trials at four thermally diverse tropical testing sites, ranging from lowland to extreme highland (mean growing season temperature range 13.2–24.6°C). Traits closely related with adaptation, such as biomass and grain yield, yield components, days from sowing to male and female flowering, total leaf number, plant height and number of primary tassel branches (TBN), were analyzed. A large line × environment interaction was observed for most traits. The genetic basis of this interaction was reflected by significant, but systematic, changes from lowland to highland sites in the correlation between the trait value and genomic composition (designated by the proportion of marker alleles with the same origin). Joint analysis of quantitative trait loci (QTLs) over sites detected 5–8 QTLs for each trait (except disease scores, with data only from one site). With the exception of one QTL for TBN, none of these accounted for more than 15% of the total phenotypic variation. In total, detected QTLs accounted for 24–61% of the variation at each site on average. For yield, yield components and disease scores, alleles generally favored the site of origin. Highland-derived alleles had little effect at lowland sites, while lowland-derived alleles showed relatively broader adaptation. Gradual changes in the estimated QTL effects with increasing mean site temperature were observed, and paralleled the observed patterns of adaptation in highland and lowland germplasm. Several clusters of QTLs for different traits reflected the relative importance in the adaptation differences between the two germplasm types, and pleiotropy is suggested as the main cause for the clustering. Breeding for broad thermal adaptation should be possible by pooling genes showing adaptation to specific thermal regimes, though perhaps at the expense of reduced progress for adaptation to a specific site. Molecular marker-assisted selection would be an ideal tool for this task, since it could greatly reduce the linkage drag caused by the unintentional transfer of undesirable traits.
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    Selection for local adaptation in a plant breeding programme (1991)
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    Theoretical and applied genetics 82 (1991), S. 363-367 
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    ISSN: 1432-2242
    Keywords: Adaptation ; Varietal stability ; GE interactions ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Regressions of yields of cultivars upon means of sets of cultivars over diverse environments are often used as measures of stability/adaptability. Prolonged selection for performance in environments of high yield potential has generally led to unconscious selection for high regressions. If adaptation to poor environments is required (as it often is in Third World agriculture), common sense suggests that low regressions could be exploited for the purpose. Simulations show that systematic selection in the poor environment is required, not merely trials of potential cultivars after selection in a good environment. In effect, systematic exploitation of a GE interactions effect is proposed. The effects are large enough to reduce correlated responses in different environments to zero. Orderly experimental studies are needed but not available. What information there is does not disagree with the theory developed here.
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    Geographical variation in heading traits in wild emmer wheat, Triticum dicoccoides. I. Variation in vernalization response and ecological differentiation (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 546-552 
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    ISSN: 1432-2242
    Keywords: Key words Vernalization ; Narrow-sense earliness ; Adaptation ; Ecological differentiation ; T. dicoccoides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Geographical variation in vernalization response and narrow-sense earliness was investigated for accessions of wild emmer wheat, Triticum dicoccoides, collected in Israel. Wide variation between and within populations was observed in both characters. The analysis of vernalization response showed that 2 accessions from Tabigha were of a strong spring growth habit, and thus wild emmer wheat was classified into four types, i.e., strongly spring type, moderately spring type, moderately winter type, and strongly winter type, according to their vernalization response. Whereas winter types were frequently found in most populations except that of Tabigha, the distribution of spring types was sporadic and restricted to warmer areas. It was thus suggested that spring type in T. dicoccoides might have evolved from a winter prototype as an adaptation to warmer conditions. Within moderately winter and moderately spring types, quantitative differences in vernalization response, measured as Dof70/Dof20 and Dof20/Dof0, were observed between populations. Inter- and intra-population variation in vernalization response could be explained to some extent by the difference in growing conditions at each habitat. It was clearly indicated that environmental heterogeneity caused ecogenetic differentiation in wild emmer wheat in Israel. Wild emmer wheat also varied considerably for narrow-sense earliness, ranging from 32.9 days to 69.5 days among accessions. However, it was difficult to explain its geographical variation simply by a linear relationship with environmental factors, and a nonlinear relationship and/or unknown microgeographic heterogeneity may be responsible.
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    Interrelationships among stabilities of important agronomic traits in sugarcane (1987)
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    Theoretical and applied genetics 74 (1987), S. 310-316 
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    ISSN: 1432-2242
    Keywords: Stability variance ; Genotype x environment interaction ; Adaptation ; Saccharum ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stability-variance statistic, ĝs i 2 , measures the contribution of the ith genotype to genotype x environment interaction. In addition to the knowledge of cultivar stability for an agronomic trait, information on whether stability of one trait can be used to predict stability of another should be useful to breeders. Three separate groups of data, respectively involving CP 79 series, CP 80 series, and CP 81 series experimental clones of sugarcane (Saccharum spp.) were used in this study. Rank-correlation coefficients (rs) between ranks of genotypes for ĝs i 2 's for paired traits indicated in both plant-cane and ratoon crops that stability of tons per hectare of sugar can be predicted from the stability of tons per hectare of cane (THC) and also, to a lesser extent, from the stability of stalk number. The stability of THC also can be reasonably well predicted from the stability of stalk number. Brix stability may give some indication of the stabilities for percentage sucrose and sugar concentration (SC). The ĝs i 2 's for percentage sucrose and SC were almost identical in the CP 79 and CP 81 series (rs varied from 0.93, P〈0.01, in plant-cane crop for CP 79 series to 0.98, P〈0.01, in plant-cane crop for CP 81 series). Whether correlations were based on ĝs i 2 's estimated across locations within crops or across crops, the magnitude of rs was about the same. Means of various traits were not correlated with their respective ĝs i 2 's (for CP 81 series), indicating that identification and selection of high-yielding sugarcane genotypes with a relatively high degree of stability of performance across test environments should be possible.
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    Regression analysis of yield stability is strongly affected by companion test varieties and locations — examples from a study of Nordic barley lines (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 468-476 
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    ISSN: 1432-2242
    Keywords: Adaptation ; Barley ; Genotype x environment interaction ; Regression analysis ; Repeatability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The suitability of regression analysis for studying the phenotypic stability of grain yield was investigated using a collection of 220 Nordic barley lines. Linear regression explained 26–52% of the genotype x environment (GE) interactions in different groupings of the material. The regression coefficient, b i , measures the yield response of the i-th genotype to improved environmental conditions. Deviations from regression, S di 2 , have been used to estimate Tai's stability parameter, λ i , which is a measure of the phenotypic yield stability in the agronomic sense. Repeatability of b i , λ i , and grain yield was studied by means of correlations between estimates obtained in each experimental year. Yield had the highest repeatability, with correlations between years ranging from 0.57 to 0.85. In this study, regression coefficients and λ i -values were not repeatable, i.e. genotypes reacted differentially to the yearly climatic variations. Six-rowed (6r) barleys had higher responsiveness, but lower mean yields, than two-rowed (2r) barleys. This is partly due to the history of selection of 6r-barleys, which mainly originate from regions with low potential yield levels, i.e. Finland and Norway. In general, responsiveness and stability were not correlated with yield. The highest-yielding lines had b i ≈1. The response pattern of the different types of barleys used in this study show that responsiveness can be changed by recombination.
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    URL: http://dx.doi.org/10.1007/BF00223192
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    Genetic basis of adaptation: flowering time in Arabidopsis thaliana (1997)
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    Theoretical and applied genetics 95 (1997), S. 573-583 
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    ISSN: 1432-2242
    Keywords: Key words QTL-mapping ; Adaptation ; Flowering time ; Arabidopsis thaliana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have mapped QTLs (quantitative trait loci) for an adaptive trait, flowering time, in a selfing annual, Arabidopsis thaliana. To obtain a mapping population we made a cross between an early-summer, annual strain, Li-5, and an individual from a late over-wintering natural population, Naantali. From the backcross to Li-5 298 progeny were grown, of which 93 of the most extreme individuals were genotyped. The data were analysed with both interval mapping and composite interval mapping methods to reveal one major and six minor QTLs, with at least one QTL on each of the five chromosomes. The QTL on chromosome 4 was a major one with an effect of 17.3 days on flowering time and explaining 53.4% of the total variance. The others had effects of at most 6.5 days, and they accounted for only small portions of the variance. Epistasis was indicated between one pair of the QTLs. The result of finding one major QTL and little epistasis agrees with previous studies on flowering time in Arabidopsis thaliana and other species. That several QTLs were found was expected considering the large number of possible candidate loci. In the light of the suggested genetic models of gene action at the candidate loci, epistasis was to be expected. The data showed that major QTLs for adaptive traits can be detected in non-domesticated species.
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    URL: http://dx.doi.org/10.1007/s001220050598
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    Several QTLs involved in osmotic-adjustment trait variation in barley (Hordeum vulgare L.) (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 688-698 
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    ISSN: 1432-2242
    Keywords: Key words Water stress ; Barley ; Osmotic adjustment ; Adaptation ; QTL ; Synteny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Osmotic adjustment (OA) was previously demonstrated to be an important adaptive mechanism of drought tolerance in cereals. In order to determine which genomic regions are involved in OA variation, 187 barley (Hordeum vulgare L.) recombinant inbred lines (RILs) derived from a cross between Tadmor (drought tolerant) and Er/Apm (susceptible) were studied in a growth chamber for their OA capacity (through correlated traits and by calculation), at an early growth stage and under two water treatments (soil moisture of 14% and 100% of field capacity). The continuous distribution of the traits and their broad-sense line heritabilities, ranging from 0.04 to 0.44, indicated that OA and related traits should have a polygenic nature. A subset of 167 RILs were also genotyped using 78 RFLP, 32 RAPD and three morphological markers and a linkage map was constructed. Despite strong environmental effects acting on the traits, interval mapping and single-marker ANOVA allowed the detection of three QTLs for relative water content (RWC), four QTLs for osmotic potential (ψπ), two QTLs of osmotic potential at full turgor (ψπ100) and one QTL for osmotic adjustment at a soil moisture of 14% field capacity. For the irrigated treatment, only two QTLs were detected: one for RWC and one for ψπ100. Two chromosomal regions were involved in several OA-related trait variations and could be considered as regions controlling OA; these were present on chromosome 1 (7H) and chromosome 6 (6H), whereas other regions were specific for one trait. No major QTL was found. However, the genomic region involved in OA-related traits on chromosome 1 (7H) in barley seemed to be conserved for OA variation among cereals. Epistatic effects, with or without additive effects, acted on the traits.
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    URL: http://dx.doi.org/10.1007/s001220050790
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    Genotype X environment interaction for bunch yield and its components in the oil palm (Elaeis guineensis, Jacq.) (1983)
    Springer
    Theoretical and applied genetics 64 (1983), S. 133-136 
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    ISSN: 1432-2242
    Keywords: Stability ; Adaptation ; Fitness trait ; Bunch yield ; Oil palm ; Elaeis guineensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary There were significant differences between hybrids for number of bunches (NB), mean bunch weight (MBW) and fresh fruit bunch yield (FFB). For the hybrid population as a whole, significant hybrid X year (environment) effects were also observed for the two yield components and for yield per se. The linear component of the hybrid X year effect was also significant. There were highly significant and positive correlations between FFB, NB and MBW hybrid means and the regression co-efficients of the hybrid means on the environmental index. There were no significant associations between these means and mean square deviations from regression (s2d) for these traits.
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    URL: http://dx.doi.org/10.1007/BF00272720
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    Genotype x environment interaction in dairy cattle and its role in breeding programmes (1983)
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    Theoretical and applied genetics 66 (1983), S. 93-99 
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    ISSN: 1432-2242
    Keywords: Lactation ; Milk yield ; Herd production ; Adaptation ; Dairy cattle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eighty thousand, one hundred and eleven records of the Israeli dairy herdbook for the period of 1973–1977 were studied and examined to determine the existence of Genotype x Environment Interaction (GxE) as affecting milk yield in kg per day between calvings. Various quantitative measures of environment were used while the genotypes were evaluated as the average performance of each sire's daughters in a whole range of environments. When the environment was evaluated as level of production, the relative importance of the interaction was found to be very low. Furthermore, the linear dependence on the interaction of the individual sires with the environments was found to be inconsistent with time, meaning that no justification was found for using specific adaptation patterns of genotypes to these environments. When lactation number and given time periods were used as environments, significant interactions were found between genotypes and environments. Results of the analyses of Genotype x Lactation interaction imply that the interaction values, to a certain degree, confused the differences between the sires when based on first lactation records. We therefore conclude that the need exists to expand the basis of sire evaluation, including the addition of data on successive lactation periods beyond the first one. We maintain that the genetic characteristic for this phenomenon is the “lactations development” of a sire, i.e., the performance of its daughters during the different lactations. The “maturing rhythm” of a sire may be regarded as a dynamic expression of the genetic makeup controlling lactation development. Furthermore, the prospect of selecting sires of bulls for early or late maturing could provide a new tool for the dairy cattle breeder.
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    URL: http://dx.doi.org/10.1007/BF00265180
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    Natural selection causing microsatellite divergence in wild emmer wheat at the ecologically variable microsite at Ammiad, Israel (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 985-999 
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    ISSN: 1432-2242
    Keywords: Key words Natural selection ; Microecological diversity ; Microsatellites ; Adaptation ; T. dicoccoides ; Wild emmer wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic diversity at 28 microsatellite loci was studied in a natural population of Triticum dicoccoides at the Ammiad microsite, north of the Sea of Galilee, Israel. This microsite was subdivided into four major habitats, North, Valley, Ridge and Karst, and further subdivided into nine subhabitats. The units thus defined showed strong and highly significant differentiation in ecological factors; in particular with respect to cover, proximity and height of rocks, and surface soil moisture after early rains. The results showed that allele distributions at microsatellite loci were nonrandom and associated with habitats. Significant genetic differentiation and variation in repeat number were found among subpopulations in the four major habitats and nine subhabitats. Habitat-specific and -unique alleles and linkage disequilibria were observed in the Karst subpopulation. The subpopulations dwelling in drier habitats and subhabitats showed higher genetic diversities at microsatellite loci. These results suggest that natural selection, presumably through aridity stress, acts upon microsatellite divergence predominantly on noncoding sequences, thereby contributing to differences in fitness.
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    Application of microsatellites in wheat (Triticum aestivum L.) for studying genetic differentiation caused by selection for adaptation and use (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 242-248 
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    ISSN: 1432-2242
    Keywords: Key words DNA markers ; Genetic diversity ; Agroecological area ; Quality ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  For studying genetic differentiation caused by selection for adaptation and end-use, the allele frequencies of 42 microsatellites (MS), representative of the three wheat genomes, were analysed in a total of 60 wheat cultivars. The cultivars originate from three agroecological areas (AEAs) – Germany, Austria and Hungary – and represent equal numbers of ’quality wheats’ and ’feed wheats’ for each country. For the 42 loci, 202 alleles were detected using PAGE and silver staining. The average number of alleles per locus was 4.8, including four monomorphic loci. For 16 loci, null alleles were detected. Cluster analysis clearly differentiated the varieties according to the three AEAs and, within each AEA, into quality wheats from feed wheats. Analysis of variance revealed highly significant differences of distance data between AEAs as well as between quality groups. The correlation between genetic distance (GD) and pedigree data (coefficient of diversity, COD) was r s=0.45. The results have proven the excellent resolving power of MS in varietal differentiation, which arises through breeding under specific environmental conditions, and for different end-use.
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    Simulating convesations: The communion game (1995)
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    AI & society 9 (1995), S. 116-137 
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    ISSN: 1435-5655
    Keywords: Adaptation ; AI ; Conversation ; Corrdination ; Imitation game ; Language ; Machine learning ; Turing test ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In their enthusiasm for programming, computational linguists have tended to lose sight of what humansdo. They have conceived of conversations as independent of sound and the bodies that produce it. Thus, implicit in their simulations is the assumption that the text is the essence of talk. In fact, unlike electronic mail, conversations are acoustic events. During everyday talk, human understanding depends both on the words spoken and on fine interpersonal vocal coordination. When utterances are analysed into sequences of word-based forms, however, these prosodic aspects of language disappear. Therefore, to investigate the possibility that machines might talk, we propose acommunion game that includes this interpersonal patterning. Humans and machines would talk together and, based on recordings of them, a panel would appraise the relevant merit of each machine's simulation by how true to life it sounded. Unlike Turing's imitation game, the communion game overtly focuses attention, not on intelligence, but on language. It is designed to facilitate the development of social groups of adaptive robots that exploit complex acoustic signals in real time. We consider how the development of such machines might be approached.
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    CADREM: A case-based system for conceptual structural design (1997)
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    Engineering with computers 13 (1997), S. 153-164 
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    ISSN: 1435-5663
    Keywords: Artificial intelligence ; Case-based reasoning ; Design methods ; Representation ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper proposes an approach for reusing design methods from past designs for solving new problems. This is an application of case-based reasoning to design. The proposed approach is implemented as a prototype system called CADREM. CADREM has been tried in the domain of conceptual structural design of buildings. First, a description of case-based reasoning is given followed by its application in design. Then follows a description of the proposed approach and CADREM. Sample outputs from CADREM are also included.
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    URL: http://dx.doi.org/10.1007/BF01221212
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    The role of culture in the technological advancement process (1993)
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    AI & society 7 (1993), S. 248-252 
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    ISSN: 1435-5655
    Keywords: Culture ; Technology ; Cold utilitarianism ; Adaptation ; Civilization ; Western culture ; Eastern culture ; Instrumentality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The role of cultural models in the process of adaptation to the new technologies is very different according to different civilizations. Some basic cultural items seem to be particularly crucial, such as, for example, the levels of pragmatism or rationalism which characterize a civilization or some periods of its history. This paper presents a sketch aimed at setting up a comparison between Western and Eastern cultures facing the problem of adapting to new technologies. The concept ofcold utilitarianism is introduced. It allows a way of defining adaptation which is only partial and contradictory in Western culture, while it completely describes, though perhaps provisionally, the Eastern way of making and using technology.
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    Alkalosis and renal excretion of ammonia by rat kidney (1988)
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    Cellular and molecular life sciences 44 (1988), S. 453-455 
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    ISSN: 1420-9071
    Keywords: Adaptation ; diffusion trapping ; sulfate infusion ; PpH ; UpH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Upon sulfate administration, UpH falls more in alkalotic rats than in controls. Alkalosis can lead to a reduction in UNH 3V at highly acidic urine. The significance of this process is doubtful at UpH ranging from about 6 to 7. At lower UpH less NH3 would be excreted, thereby less H+ would be trapped in urine and some acid would be conserved.
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    Inbreeding considerations in a REM sleep model for rat swimming activity (1986)
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    Cellular and molecular life sciences 42 (1986), S. 134-136 
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    ISSN: 1420-9071
    Keywords: Adaptation ; animal models ; animal vendor effects ; evolutionary mechanisms ; rat strain effects ; rat swimming ; sleep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Over the past few years, our laboratory group has elaborated a repeated measures rat swimming test. It provides an animal base for showing that the REM sleep mechanism is important to both emotional responsiveness and environmental adaptations. All of that work has been done with Sprague-Dawley rats obtained from a local supplier. Work done with two European rat stocks (by researchers in France and The Netherlands) shows general agreement with our own. In this presentation, we directly compare rats derived from an English vendor's Sprague-Dawley stock with the U.S. based Sprague-Dawley stock which we have been using. We also make strain comparisons via the F344 and the Long Evans strains. Although the literature has numerous examples of swimming test differences between inbred and wild rat stocks, strain difference effects have not been reported. We report that there are significant differences attributable to inbred strain but not to vendor on this measure.
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    Biochemical ecology of deep-sea animals (1992)
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    Cellular and molecular life sciences 48 (1992), S. 537-543 
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    ISSN: 1420-9071
    Keywords: Adaptation ; deep sea ; hydrostatic pressure ; hydrothermal vents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Deep-sea ecosystems contain unique endemic species whose distributions show strong vertical patterning in the case of pelagic animals and sharp horizontal patterning in the case of benthic animals living in or near the deep-sea hydothermal vents. This review discusses the biochemical adaptations that enable deep-sea animals to exploit diverse deep-sea habitats and that help establish biogeographic patterning in the deep-sea. The abilities of deep-sea animals to tolerate the pressure and temperature conditions of deep-sea habitats are due to pervasive adaptations at the biochemical level: enzymes exhibit reduced perturbation of function by pressure, membranes have fluidities adapted to deep-sea pressures and temperatures, and proteins show enhanced structural stability relative to homologous proteins from cold-adapted shallow-living species. Animals from the warmest habitable regions of hydrothermal vent ecosystems have enzymes and mitochondria adapted to high pressure and relatively high temperatures. The low metabolic rates of bathypelagic fishes correlate with greatly reduced capacities for ATP turnover in locomotory muscle. Reduced light and food availability in bathypelagic regions select for low rates of energy expenditure in locomotory activity. Deep-sea animals thus reflect the importance of biochemical adaptations in establishing species distribution patterns and appropriate rates of metabolic turnover in different ecosystems.
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    The prospects for an evolutionary psychology: Human language and human reasoning (1996)
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    Minds and machines 6 (1996), S. 541-557 
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    ISSN: 1572-8641
    Keywords: Adaptation ; cognition ; evolutionary psychology ; human evolution ; language ; rationality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Philosophy
    Notes: Abstract Evolutionary psychology purports to explain human capacities as adaptations to an ancestral environment. A complete explanation of human language or human reasoning as adaptations depends on assessing an historical claim, that these capacities evolved under the pressure of natural selection and are prevalent because they provided systematic advantages to our ancestors. An outline of the character of the information needed in order to offer complete adaptation explanations is drawn from Robert Brandon (1990), and explanations offered for the evolution of language and reasoning within evolutionary psychology are evaluated. Pinker and Bloom's (1992) defense of human language as an adaptation for verbal communication, Robert Nozick's (1993) account of the evolutionary origin of rationality, and Cosmides and Tooby's (1992) explanation of human reasoning as an adaptation for social exchange, are discussed in light of what is known, and what is not known, about the history of human evolution. In each case, though a plausible case is made that these capacities are adaptations, there is not enough known to offer even a semblance of an explanation of the origin of these capacities. These explanations of the origin of human thought and language are simply speculations lacking the kind of detailed historical information required for an evolutionary explanation of an adaptation.
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    Brain morphology and turbidity preference in Notropis and related genera (Cyprinidae, Teleostei) (1992)
    Springer
    Environmental biology of fishes 33 (1992), S. 153-165 
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    ISSN: 1573-5133
    Keywords: Neuroanatomy ; Ecology ; Vision ; Olfaction ; Gustation ; Plasticity ; Adaptation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The size of seven neural structures was compared in 51 species of Notropis, Pteronotropis, Cyprinella, Luxilus, Lythrurus, and Hybopsis, and related to the turbidity of the species& habitat. This last parameter was assessed for each species by personal communication with 42 ichthyologists. To control for size differences among species, all analyses were performed on the residuals from a regression of each character on standard length. Principal components analysis (PCA) of the residuals produced four significant PC-axes that together explained 65% of the total variation represented in the original variables. The size of brain structures concerned with vision, olfaction, and gustation was correlated with habitat turbidity. Two-way Analyses of Covariance (ANCOVAs) revealed significant differences between species in the size of all structures. Sexual dimorphism was found in the size of the olfactory bulb and the cerebellum, and significant two-way interactions (species vs. sex) were detected for the telencephalon, optic lobes, cerebellum, vagal lobe, and the eye. Cluster analysis indicated that neither similar turbidity preference nor shared phylogeny is alone sufficient to explain the observed differences in brain morphology.
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    Design, purpose and function in evolution: meditations on a classical problem (1988)
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    Environmental biology of fishes 22 (1988), S. 241-247 
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    ISSN: 1573-5133
    Keywords: Adaptation ; Natural selection ; Survival ; Microevolution ; Macroevolution ; Darwin ; Lamarck ; Exaptation ; Aptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    Metabolic responses to food deprivation and refeeding in juveniles of Rutilus rutilus (Teleostei: Cyprinidae) (1993)
    Springer
    Environmental biology of fishes 36 (1993), S. 73-81 
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    ISSN: 1573-5133
    Keywords: Tissue water ; Protein ; Glycogen ; Enzymes of energy metabolism ; Stress ; Adaptation ; Recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Effect of food deprivation and refeeding on metabolic parameters were studied in juvenile Rutilus rutilus, weighing 280–460 mg. Tissue hydration increased with the length of the starvation period, reaching a new steady state after 4–5 weeks. Total protein concentration remained constant at about 60% of dry body mass. The concentration of glycogen decreased during food deprivation, a new steady state being reached at about 30% of control values after 4 weeks. Refeeding caused a dramatic increase of glycogen concentration which exceeded the value in fed controls by 6- to 9-fold. This is seen as a tactic for rapid storage of food energy, to be used later for the synthesis of body materials. With respect to their responses to food deprivation the 12 enzymes investigated formed four groups: (1) activity unaffected by food deprivation or refeeding (COX, THIOL, CK, GOT); (2) activity drops to about 60% of control value during the initial phase of food deprivation but remains constant thereafter (PK, LDH, Pase); (3) slow but continuous decrease in activity during the whole period of starvation, i.e. up to 7 weeks (PFK, OGDH, CS, FBPase); (4) activity increases during food deprivation, decreases again upon refeeding (GPT). A model is discussed which distinguishes between four phases in the general response of young fish to food deprivation and refeeding: stress, transition, adaptation, and recovery.
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    Perspectives on the ecomorphology of bony fishes (1995)
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    Environmental biology of fishes 44 (1995), S. 11-20 
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    ISSN: 1573-5133
    Keywords: Morphology ; Ecology ; Form ; Biological role ; Performance ; Ontogeny ; Optimization ; Phylogeny ; Constraints ; Adaptation ; Fundamental niche ; Realized niche
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The field of ecomorphology has a long history with early roots in Europe. In this half of the century the application of ecomorphology to the biology of fishes has developed in the former Soviet Union, Poland and Czechoslovakia, The Netherlands, and in North America. While the specific approaches vary among countries, many North American studies begin by comparing morphological variation with variation in ecological characteristics at the intra or interspecific levels. These initial correlative studies form the ground work for hypotheses that explore the mechanistic underpinnings of the observed ecomorphological associations. Supporting these mechanistic hypotheses are insights from functional studies which demonstrate the limits to potential resource use resulting from a particular morphology; however, the actual resource use is likely to be more limited due to additional constraints provided by internal (e.g., behavior, physiology) and external (e.g., resource abundance, predator distribution) factors. The results from performance studies in the laboratory or field can be used to test specific ecomorphological hypotheses developed from the initial correlational and functional studies. Such studies may, but rarely do, incorporate an ontogenetic analysis of the ecomorphological association to determine their effect on performance. Finally, input from phylogenetic analyses allow an investigator to examine the evolution of specific features and to assess the rates and directionality of character evolution. The structural and ecological diversity of fishes provides a fertile ground to investigate these interactions. The contributions in this volume highlight some of the specific directions for ecomorphological research covering a variety of biological processes in fishes. These include foraging, locomotion, reproduction, respiration, and sensory systems. Running through these papers are new insights into universal ecomorphological issues, i.e., the relationships between form and ecological role and the factors that modify these relationships.
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    Initial feeding time of Atlantic salmon,Salmo salar, alevins compared to river flow and water temperature in Norwegian streams (1991)
    Springer
    Environmental biology of fishes 30 (1991), S. 379-385 
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    ISSN: 1573-5133
    Keywords: Adaptation ; Development time ; Strategy ; Salmonid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The time of initial feeding of Atlantic salmon,Salmo salar, alevins in ten geographically widespread Norwegian streams was estimated theoretically by combining data on spawning time and models describing the time from fertilization to hatching and from hatching to initial feeding at different temperatures. The point of initial feeding was correlated with water flow and water temperature regimes. Initial feeding was avoided in all rivers during spring peak flow, and before water temperature reached 8°C. Two different strategies were indicated: (1) initial feeding may take place before the culmination of the spring flow or (2) after the peak spring flow. The choice of strategy depends on temperature and flow regimes in each river.
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    Fish ecology and management of the Sepik-Ramu, New Guinea, a large contemporary tropical river basin (1993)
    Springer
    Environmental biology of fishes 38 (1993), S. 345-368 
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    ISSN: 1573-5133
    Keywords: Ichthyofauna ; Colonisation ; Adaptation ; Speciation ; Diversity ; Zoogeography ; Habitats ; Fish catches ; Fish introductions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The ichthyofauna of the Sepik-Ramu basin is composed of diadromous species and the freshwater derivatives of marine families. Fish species diversity, ichthyomass and fish catches are low even by Australasian standards. Three major factors have produced the depauperate ichthyofauna and restricted fishery within the basin: First, the zoogeographic origins of the ichthyofauna. Australasian freshwater fishes, being mainly derived from marine families, generally exhibit ecological characteristics that have evolved for life in estuaries, not rivers. This has led to peculiarities in river fish ecology and explains the probable low fish production from rivers in this region in general. Several important riverine trophic resources are not exploited by the Australasian freshwater ichthyofauna. The modes of reproduction amongst the Australasian freshwater ichthyofauna have limited the colonisation and exploitation of floodplain habitats. Second, Sepik-Ramu lowland habitats, especially floodplains, are very young. This has resulted in low fish species diversity in lowlands, whilst diversity at higher altitudes is equable, in comparison to river systems in southern New Guinea/ northern Australia. Third, the Sepik-Ramu lacks an estuary in sharp contrast to river systems in southern New Guinea or northern Australia. Most of the 18 families of Australasian fishes missing from the Sepik-Ramu are probably absent because of this factor alone. In particular, the Sepik-Ramu has not been colonised by any family of fishes having pelagic eggs, resulting in the loss from the fauna of the few Australasian fish taxa with high reproductive rates. Consequently, the general problems with river fish ecology in Australasia are exacerbated within the Sepik-Ramu by the particular development and morphology of the basin. Fish species diversity in the Sepik-Ramu is low, even in comparison with those taxa representative of marine families resident in rivers in nearby zoogeographic regions (S.E. Asia) whose ichthyofaunas are otherwise dominated by freshwater dispersant groups. The Sepik-Ramu ichthyofauna is considered noteworthy for what is absent, not what is present. Ichthyomass and fish production can be increased by fish species introductions whilst, in theory, biodiversity of the native fish fauna can be maintained. The directions in which ecological evaluations of proposed introductions might proceed in practice for the Sepik-Ramu are discussed but are constrained by the lack of knowledge on species interactions from other areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007528
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    Early ontogeny of white sucker,Catostomus commersoni, with steps of saltatory development (1980)
    Springer
    Environmental biology of fishes 5 (1980), S. 191-224 
    Details
    ISSN: 1573-5133
    Keywords: Adaptation ; Benzidine stain ; Catostomid ; Discontinuity theory ; Ecomorphology ; Embryology ; Fish ; Haemoglobin stain ; Hatching ; Peroxidase ; Thresholds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Frequent and detailed observations of arbitrary stages revealed a saltatory pattern of development in the early ontogeny of fluvial spawning white sucker. Considered as adaptations for respiration were: i) expansion of the surface area of the yolk through a change in yolk shape, ii) the presence of carotenoid pigment in the yolk, iii) a large caudal vein sinus, iv) coverage of the yolk surface with capillaries of bilaterally paired vitelline plexi, and v) a large pair of vitelline veins. The ability to swim developed slowly and well after hatching. Young suckers would therefore spend most of the eleutheroembryonic phase in the interstices of the rock substrate of the spawning ground. The change from a benthic to pelagic mode of existence occurred with swimbladder inflation and before the start of exogenous feeding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005355
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  • 96
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    Local variability in population structure and density of the protogynous reef herbivoreSparisoma viride (1996)
    Springer
    Environmental biology of fishes 47 (1996), S. 65-80 
    Details
    ISSN: 1573-5133
    Keywords: Adaptation ; Territoriality ; Life history ; Mating ; Grazing pressure ; Coral reef ; Reproduction ; Scaridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis We compare the (relative) abundance of life phases [juveniles (JU), initial phase (IP) and terminal phase (TP) fish], social categories (territorial and group adults), and fish following alternative mating styles, in three local populations of the protogynous reef herbivore,Sparisoma viride, on the fringing reef of Bonaire (Netherlands Antilles). In order to determine the adaptive significance of variations in social organization, they are related to the density of conspecifics and other herbivores and to the availability of food, shelter and mating sites. The most striking difference is the high abundance of JU and group fish at one location (Playa Frans) and the total absence of group fish at another (Red Slave). These differences are coherent with a gradient in population density, total herbivore density, scarid grazing pressure, and reproductive output, all of which are highest at Playa Frans and lowest at Red Slave. Exposure to waves and currents shows an inverse trend. The differences in the relative abundance of territorial fish can be explained by the concept of economic defendability, which is reduced at higher population density. In a life history context, small TP group males represent ‘bachelors’ that sacrifice current reproduction for better future prospects. As predicted by life history theory, early sex change is promoted at sites where the future rewards are higher (higher spawning rates of large TP males) and where the costs incurred during the bachelor phase are reduced (more spawning opportunities for group TP males). At Red Slave an alternative male mating style (‘streaking’) appears to be promoted by the lack of a refuge for group TP males and by a dense gorgonian canopy, allowing IP males to reside inside territories. We conclude that most observed differences in population structure can be considered adaptive in an ecological and in a life history context. Population density is a major factor in both contexts. Analysis of the variability in adult density in relation to JU density and the availability of food and shelter indicates that theS. viride populations at Bonaire are not totally controlled by stochastic processes. Considering the small spatial scale and the high dispersal of the planktonic embryos and larvae, the observed variability in behavioural and life history traits ofS. viride points to a high degree of phenotypic plasticity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002380
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  • 97
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    Concordant variation in thermal tolerance and allozymes of the red shiner, Notropis lutrensis, inhabiting tailwater sections of the Brazos River, Texas (1985)
    Springer
    Environmental biology of fishes 13 (1985), S. 49-57 
    Details
    ISSN: 1573-5133
    Keywords: Adaptation ; Dam ; Enzymes ; Electrophoresis ; Evolution ; Genetics ; Physiology ; Regulated streams ; Thermal maximum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Critical thermal maxima (CTM) and genetic variation were compared for red shiners, Notropis lutrensis, from regulated and unregulated sites on the Brazos River in northcentral Texas. Tailwater fish acclimated to 25°C had significantly lower CTM's than those from a site upstream from the dam and unregulated downstream sites. Significantly different intrasite variances were observed, with two- and four-fold larger CTM variances in fish from within 1 km and 30 km of the dam. Genetic variation was determined from electrophoretic comparisons at 21 structural gene loci. Mean heterozygosity was greatest at regulated sites. Tests for locus heterogeneity at five variable loci indicated that regulated and unregulated populations are not homogeneous. Fish under regulation were genetically more similar to each other than they were to those not affected by regulation. The proportions of the gene variance attributable to habitat alteration were partitioned, and fully one-third of the gene variation was attributed to stream regulation. Patterns of variation in thermal tolerance and metabolic enzymes in the red shiner correlated closely with temperature regimes associated with hypolimnion release from the dam. These adaptive responses have occurred in less than 40 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004855
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  • 98
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    Microbial ecology of the subsurface at an abandoned creosote waste site (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 109-120 
    Details
    ISSN: 1476-5535
    Keywords: Ground water ; Biodegradation ; Hydrocarbon ; Adaptation ; Subsurface ; Creosote ; Microorganism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The microbial ecology of pristine, slightly contaminated, and heavily contaminated subsurface materials, and four subsurface materials on the periphery of the plume at an abandoned creosote waste site was investigated. Except for the unsaturated zone of the heavily contaminated material, mineralization of glucose (13.5 ppb) indicated a metabolically active microflora in all subsurface materials. However, mineralization (〈40%) of naphthalene, phenanthrene, and 2-methylnaphthalene was observed in contaminated material and material from the periphery of the plume, but not in pristine material. Pentachlorophenol was mineralized in material from the periphery of the plume. Inorganic and organic nutrient amendments and changes in pH and temperature did not increase the extent of mineralization of the aromatic compounds. An array of organic compounds found in creosote were biotransformed in contaminated ground water; however some compounds were still detected after 7 months of incubation. The data suggest that the subsurface microflora in slightly and heavily contaminated subsurface materials and materials from the periphery of the plume has adapted to degrade many compounds found in creosote.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569795
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  • 99
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    Nitrate production in the rhizosphere of Plantago species (1981)
    Springer
    Plant and soil 61 (1981), S. 43-52 
    Details
    ISSN: 1573-5036
    Keywords: Adaptation ; Allelopathy ; Ecophysiology ; Grassland ; Plantago ; Nitrate production ; Nitrate reductase ; Nitrate uptake ; Nitrification ; Nitrifying bacteria ; Rhizosphere ; Root environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The production of nitrate in an old established dune grassland soil and its uptake by plants was studied by comparing amounts of mineral nitrogen and numbers of nitrifying bacteria in the rhizosphere on the one hand, and on the other accumulated nitrate and levels of nitrate reductase (NaR) of individual plants of three Plantago species,i. e., P. major, P. lanceolata andP. coronopus. For these three Plantago species andP. media basal levels of NaR in the absence of nitrate were determined in plants grown in culture solutions. The basal NaR levels ofP. major andP. media (species occurring on nutrient-rich soils) were significantly higher than those ofP. lanceolata andP. coronopus (species found on nutrient-poor soils). NaR activity increased in the presence of nitrate and was suppressed by ammonium. From the numbers of nitrifying bacteria in the rhizosphere and NaR activity in the leaves it was concluded that nitrate was produced in the root environments of the three Plantago species and that the compound was taken up by the plants. NaR activities and numbers of nitrifying bacteria were higher for individuals ofP. major than for those ofP. lanceolata andP. coronopus. No correlation was found between the ammonium levels and the numbers of nitrifying bacteria in the soil, and no indications of inhibition of nitrifying bacteria in the rhizosphere were obtained. For individuals ofP. lanceolata a correlation was found between the numbers of nitrifying bacteria in the soil and NaR activity in the leaves. The results are discussed in relation to the ecological habitats of the three species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277361
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  • 100
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    Variation within improved cultivars and landraces of lucerne in Central Italy (1994)
    Springer
    Euphytica 77 (1994), S. 199-203 
    Details
    ISSN: 1573-5060
    Keywords: Adaptation ; cultivars ; genetic erosion ; human selection ; landraces ; seed legislation ; variation ; lucerne ; Medicago sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A variety must be distinguishable, uniform, stable and of sufficient productivity to be officially registered. In Italy landraces of lucerne are still widely used because they are characterized by a good persistence and productivity in their area of origin and adaptation. The landrace from Casalina (20 km south of Perugia, Central Italy) has higher dry matter production than many other commercial cultivars. The objective of this paper was to measure the variation of the landrace Casalina and compare it with that of the commonest cultivars available on the market and with some lines selected from the landrace Casalina. The experiment consisted of 11 entries: Casalina, two selections from Casalina (one for high seed yield and one for frequent cuttings), the registered landrace Italia Centrale and 7 registered cultivars. Each entry was represented by 80 genotypes transplanted in the field 60×40 cm apart in a randomized block design with 4 replications. In 1991 the following characters were recorded on a single plant basis: time of first flowering, height, number of shoots and dry matter yield at the first harvest, time of second flowering, leafiness, height, number of shoots and dry matter yield at the second harvest, height, number of shoots and dry matter yield at the third and fourth harvest. Height, number of shoots and dry matter yield at the first harvest, dry matter at the second and third harvest were recorded during the 1992 season. Casalina was as variable as the other entries in 77% of the comparisons; it was more variable in 8% of the comparisons and less variable in 15% of the comparisons. In conclusion, the variation of landrace Casalina is equal to or less than that of registered varieties so that it could be directly registered at the National Registry of Varieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262632
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