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  • Adaptation
  • Springer  (75)
  • 1990-1994  (36)
  • 1985-1989  (27)
  • 1975-1979  (12)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 109-120 
    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.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    AI & society 7 (1993), S. 248-252 
    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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  • 3
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    Springer
    Cellular and molecular life sciences 48 (1992), S. 537-543 
    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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  • 4
    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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  • 5
    Electronic Resource
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    Springer
    Journal of comparative physiology 171 (1992), S. 505-512 
    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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  • 6
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    Journal of comparative physiology 171 (1992), S. 573-581 
    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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  • 7
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    Springer
    Journal of comparative physiology 172 (1993), S. 583-591 
    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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  • 8
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    Springer
    Journal of comparative physiology 175 (1994), S. 267-278 
    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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  • 9
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    Springer
    Journal of molecular evolution 30 (1990), S. 196-201 
    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.
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  • 10
    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.
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  • 11
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    Springer
    European journal of nutrition 31 (1992), S. 178-188 
    ISSN: 1436-6215
    Keywords: Thermogenese ; Adaptation ; Energiebilanz ; Unterernährung ; Überernährung ; thermogenesis ; adaptation ; energy balance ; underfeeding ; overfeeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary In a model experiment eight adult sows were used to examine the effect of successive periods of under- and oversupply of energy (MÜMÜ) on thermogenesis and efficiency of energy utilization in comparison to a constant maintenance supply (NNNN). Each treatment sequence was assigned to each animal according to a change-over design over 8 weeks. Before and after the treatment periods all the animals were fed at maintenance level (N). Energy deficiency (M) was performed by use of a basal diet with 45 % of maintenance energy requirements and values for all the other nutrients sufficient for requirements. Normal (N) and excessive (Ü) intakes of energy was provided with supplements of starch. The total intake of gross energy during the periods MÜMÜ was exactly the same as during NNNN. Complete energy balances were performed for each animal and period as well as during the pre- and post-experimental phase. There was no or little response of altered energy intake on carbon and energy excretion in faeces, urine and methane. However, heat production was significantly decreased by 4.1 % on energy deficiency, and increased by 15.1 % during energy oversupply. Summed up over the total sequence the animals produced 5.4 % more heat on MÜMÜ than during NNNN. This response was associated with a mobilization of 1.1 MJ/d tissue energy and a decrease in body weight by 2.0 kg. The efficiency of utilization of ME was 88 % with energy undersupply and 75 % during overnutrition. Criteria of energy balance did not differ between the pre- and post-treatment periods. It could be demonstrated that the increase in energy expenditure at oversupply was entirely explainable by the so-called obligatory thermogenesis. At the energy deficiency periods the efficiency of energy utilization reflected both energy costs of ingestion and processing of nutrients as well as a slight reduction in metabolic rate. Finally, there were no residual effects of the treatment on the energy expenditure of the animals at the end of the experiment.
    Notes: Zusammenfassung In einem Modellversuch mit 8 nichtgraviden, nichtlaktierenden Sauen wurde eine alternierende Mangel- und Überfütterung an Energie über 8 Wochen im Vergleich zur Fütterung auf Erhaltungsniveau durchgeführt. Das Experiment war in Form eines changeover-Plans angelegt. Energiemangel wurde mit einer Basisration realisiert, die 45 % des energetischen Erhaltungsbedarfs lieferte, alle anderen Nähr- und Wirkstoffe aber bedarfsdeckend enthielt. Normalzufuhr an Energie und Energieüberschuß wurden durch Zulage von Stärke hergestellt. Die Zufuhr an Bruttoenergie war in der Summe von Energiemangel und Energieüberschuß exakt gleich der Fütterung auf Normalniveau. Von jedem Tier wurde in jeder Rationsperiode eine vollständige Messung der C-, N- und Energiebilanz durchgeführt. Zusätzlich wurde der Bilanzstatus aller Sauen unter Normalfütterung vor und nach den change-over-Perioden ermittelt. Die alternierende Energiezufuhr hatte keine oder nur minimale Effekte auf die C- und Energieausscheidung in Kot, Harn und CH4. Dagegen war die Wärmeproduktion bei Energiemangel signifikant um 4,1 % erniedrigt und bei Energieüberschuß um 15,1 % erhöht. In der Summe lag die Wärmebildung bei alternierender Versorgung um 5,4 % höher als bei Normalfütterung. Dies hatte eine Mobilisation von täglich 1,1 MJ Körperenergie zur Folge und erklärte auch die Abnahme der Lebendmasse der Tiere um 2,0 kg. Die Wirkungsgrade der ME beliefen sich auf 88 % bei Energiemangel und auf 75 % bei Energieüberversorgung. Die Bilanzdaten nach der Versuchsbehandlung waren gegenüber den vor Versuch ermittelten Werten nicht verändert. Unter den vorliegenden Bedingungen des Energieüberschusses konnte kein Hinweis auf eine diätinduzierte regulatorische Komponente der Thermogenese gefunden werden. Die beobachteten Effekte ließen sich vollständig durch die Theorie der obligatorischen Wärmebildung bei Nährstofftransformation erklären. Im Energiemangel war dagegen eine Adaptation der Stoffwechselrate festzustellen.
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  • 12
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    Cellular and molecular life sciences 44 (1988), S. 453-455 
    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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  • 13
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    Cellular and molecular life sciences 42 (1986), S. 134-136 
    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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  • 14
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    International journal of biometeorology 33 (1989), S. 246-250 
    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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  • 15
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    Oecologia 97 (1994), S. 179-185 
    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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  • 16
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    Oecologia 72 (1987), S. 69-76 
    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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  • 17
    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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  • 18
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    Oecologia 76 (1988), S. 553-561 
    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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  • 19
    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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  • 20
    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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  • 21
    ISSN: 1432-1939
    Keywords: Acyrthosiphon pisum ; Migration ; Adaptation ; Photoperiod
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    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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    Oecologia 76 (1988), S. 161-167 
    ISSN: 1432-1939
    Keywords: Adaptation ; Altitudinal gradients ; Herbivores ; Insect galls ; Species richness
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    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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  • 23
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    Oecologia 77 (1988), S. 533-536 
    ISSN: 1432-1939
    Keywords: Energetics ; Speciation ; Adaptation ; Spalax ehrenbergi
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    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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    European biophysics journal 3 (1977), S. 141-143 
    ISSN: 1432-1017
    Keywords: Calcium ; Limulus ; Photoreceptors ; Adaptation
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    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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    European biophysics journal 3 (1977), S. 171-173 
    ISSN: 1432-1017
    Keywords: Adaptation ; Frog ; Retina ; Rhodopsin
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    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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    European biophysics journal 3 (1977), S. 175-180 
    ISSN: 1432-1017
    Keywords: Rodopsin ; Phosphorylation ; Adaptation ; Retina ; Cyclic nucleotides
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    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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    European biophysics journal 4 (1978), S. 115-128 
    ISSN: 1432-1017
    Keywords: Adaptation ; Rod outer segment
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    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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    European biophysics journal 5 (1979), S. 231-235 
    ISSN: 1432-1017
    Keywords: Visual pigment ; Photoreceptor ; Metarhodopsin ; Adaptation
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    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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    European biophysics journal 2 (1977), S. 333-336 
    ISSN: 1432-1017
    Keywords: Photoreceptor model ; Receptor potential ; Vertebrate ; Invertebrate ; Adaptation
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    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.
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  • 30
    ISSN: 1432-0983
    Keywords: Chromosome length variants ; Adaptation ; Yeast ; Continuous culture
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    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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    Journal of comparative physiology 168 (1991), S. 151-157 
    ISSN: 1432-1351
    Keywords: Adaptation ; Information ; Unifying theory
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    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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    Archives of microbiology 108 (1976), S. 299-304 
    ISSN: 1432-072X
    Keywords: Nitrobacter ; Mixotrophic growth ; Cell-yield ; Adaptation
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    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.
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    Archives of microbiology 147 (1987), S. 117-120 
    ISSN: 1432-072X
    Keywords: Adaptation ; Ciliate ; Stentor coeruleus ; Photophobic response ; Action spectrum
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    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.
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    Archives of microbiology 112 (1977), S. 103-107 
    ISSN: 1432-072X
    Keywords: Alkaline phosphatase ; Adaptation ; Derepression ; Repression ; Phosphite ; Hypophosphite
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    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.
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  • 35
    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Adaptation ; Photosynthesis ; Carbohydrate accumulation ; Relative growth rate ; [Light-phosphate] interactions
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    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.
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    Archives of microbiology 113 (1977), S. 111-120 
    ISSN: 1432-072X
    Keywords: Adaptation ; Reduced light ; Chloroflexus ; Synechococcus ; Ecological studies ; Yellowstone ; National Park ; Hot springs
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    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.
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  • 37
    ISSN: 1432-2285
    Keywords: Adaptation ; Leaf distribution ; Mono-layer ; Multi-layer ; Understory tree species
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    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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    Journal of comparative physiology 168 (1991), S. 393-407 
    ISSN: 1432-1351
    Keywords: Electroreception ; Descending control ; Adaptation ; Pyramidal cells ; Weakly electric fish ; Sensory processing
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    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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    Journal of comparative physiology 170 (1992), S. 691-700 
    ISSN: 1432-1351
    Keywords: Adaptation ; Temporal pattern ; Olfaction ; Insect ; Pheromone ; Receptor neuron
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    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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    Theoretical and applied genetics 82 (1991), S. 363-367 
    ISSN: 1432-2242
    Keywords: Adaptation ; Varietal stability ; GE interactions ; Simulation
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    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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    Theoretical and applied genetics 74 (1987), S. 310-316 
    ISSN: 1432-2242
    Keywords: Stability variance ; Genotype x environment interaction ; Adaptation ; Saccharum ; Sugarcane
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    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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    Theoretical and applied genetics 88 (1994), S. 557-560 
    ISSN: 1432-2242
    Keywords: Zea mays L. ; Genome size ; Adaptation ; Nucleotype ; Agronomic performance
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    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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    Theoretical and applied genetics 87 (1993), S. 409-415 
    ISSN: 1432-2242
    Keywords: Genotype x environment interaction ; Adaptation ; Stability ; Desirability index
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    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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    Behavioral ecology and sociobiology 35 (1994), S. 437-443 
    ISSN: 1432-0762
    Keywords: Adaptation ; Sex ratio ; Host size ; Parasitoid wasps
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    Topics: Biology
    Notes: Abstract In behavioral ecology it is generally assumed that behavior is adaptive. This assumption is tested here for sex ratio manipulation in response to host size in the parasitoid wasp Spalangia cameroni. Females produce a greater proportion of daughters on larger hosts. If this behavior is adaptive, it is not through a positive effect of host size on the fitness of daughters, as theory suggests and as found for other species. Females that developed on larger hosts were not more successful at drilling into hosts, were not more successful at interspecific competition for hosts, and did not have greater dispersal ability as measured by wing loading (weight/area of wing and thorax). The possibility that S. cameroni's sex ratio manipulation may be adaptive through a negative effect of host size on the fitness of sons cannot be ruled out. Relative to males from larger hosts, males from smaller hosts had lower wing loading and thus potentially greater dispersal ability. The actual effect of wing loading on fitness remains to be tested.
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  • 45
    ISSN: 1432-0878
    Keywords: Antioxidant enzymes ; Adaptation ; Hyperoxia ; Oxygen toxicity ; Mitochondria ; Peroxisomes ; Cell culture ; Chinese hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To study the cellular defense mechanism against oxygen toxicity, an oxygen-tolerant cell line from Chinese hamster ovary (CHO) was obtained by multistep adaptation to increased O2 levels. The hyperoxia-adapted (HA) cells were able to proliferate under an atmosphere of 99% O2/1% CO2, an O2 tension lethal to the parental (control) cells. When grown under normoxic conditions (20% O2/1% CO2/79% N2) the cells remained tolerant for at least 8 weeks, suggesting a genetic basis for the oxygen tolerance. Compared to the parental cells, the HA cells were irregularly shaped, had larger mitochondria, contained more lipid droplets and showed a reduced growth rate. Ultrastructural morphometry revealed a 1.8-fold (p〈0.001) increase of the mitochondrial volume fraction in the HA cells, resulting from an increase in both number and average volume of the mitochondria. The volume fraction of peroxisomes was increased over two-fold in the HA cells, as appeared from a ∼1.9-fold (p〈 0.001) increase in number and a 1.2-fold (p〈0.025) increase in size. There was no evidence for ultrastructural damage in the HA cells. Specific activities of antioxygenic enzymes were considerably higher in the HA cells compared to controls: CuZn-superoxide dismutase, x 2.5; Mn-superoxide dismutase, x 2.1; catalase, x 4.0; glutathione peroxidase, x 1.9. Oxygen tolerance in CHO cells is therefore associated with increased levels of antioxygenic enzymes, confirming the proposed important role of these enzymes in the defense against oxygen toxicity.
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  • 46
    ISSN: 1432-0878
    Keywords: Hygroreceptors ; thermoreceptors ; Sensillum styloconicum ; Adaptation ; Sensory transduction ; Cryofixation ; Freeze-substitution ; Bombyx mori (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The thermo-/hygrosensitive sensilla styloconica of the silk moth Bombyx mori were studied using cryofixation and freez-substitution. These sensilla are characterized by a short poreless cuticular peg, which is double-walled in its distal part. The central lumen is innervated by the unbranched outer dendritic segments of the two presumed hygroreceptor cells. The presumed thermoreceptor cell displays lamellae below the peg base. Within the peg lumen, the dendrites are surrounded by the peridendritic dense coat and the lowdensity matrix. Below the peg base, these structures continue as the dendrite sheath, which is separated from the outer sensillum-lymph space by a layer of the trichogen cell. The central lumen, therefore, is only connected with the inner sensillum-lymph space, but the appearance of the low-density matrix, within the peg, differs from that of the sensillum lymph below the peg. In moist-adapted (24 h) sensilla, the two hygroreceptor dendrites invade the peg for three quarters and one half of its length, respectively, and fill the cross-sectional area of the lumen by 50–80%. In dry-adapted (24 h) sensilla, the dendrites terminate more proximally and fill the cross-section by ∼35%. The volume of the low-density matrix increases under dry conditions and decreases under humid conditions. At intermediate ambient humidity, the morphology of these sensilla is halfway between the dry-adapted and the moist-adapted state. The effect of dry-adaptation is reversible, so that sensilla that were first dry-adapted and then moist-adapted (24 h each) before cryofixation cannot be distinguished from moist-adapted sensilla. The reduction of the exposed length of the dendrites is interpreted as a shift of the working range of the receptors and/or protection against desiccation. The current theories of sensory transduction in hygroreceptors, in particular the hygrometer and evaporimeter hypotheses, are discussed with respect to the present findings.
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  • 47
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    Plant systematics and evolution 161 (1988), S. 35-47 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cruciferae ; Capsella bursa-pastoris ; Adaptation ; germination behaviour in natural populations ; seed dormancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germination behaviour of variousCapsella bursa-pastoris populations collected from Scandinavia, Middle Europe and the Alps, was tested in unheated, non-illuminated greenhouses (46 populations) and in growth chambers using 5–7 alternating temperature regimes (16 populations). For all populations, the influence of temperature on germination rate is straightforward: the higher the temperature, the greater the germination. Germination capacity, however, may depend on the geographical region. There is also a strong seed age effect on both, rate and capacity of germination. Once dormancy was broken, seeds from all populations were able to germinate over the entire range of temperatures. Some populations revealed a more or less pronounced temperature optimum for germination capacity, others germinated equally well over the entire temperature range. This indicates genetic heterogeneity between populations. However, no correlation between germinability and any environmental pattern was detected. The data indicate thatCapsella bursa-pastoris has adopted a germination strategy which includes a broad temperature tolerance. Germination of wildCapsella plants seems to be regulated by the factors contributing to the inception and breaking of dormancy which depend on pre- and postharvest conditions. Adaptation in germination behaviour inCapsella bursa-pastoris is different from that in other life history traits (flowering behaviour, growth form parameters).
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    Plant systematics and evolution 152 (1986), S. 277-296 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cruciferae ; Capsella bursa-pastoris ; Adaptation ; inception of flowering in natural populations ; phenotypic and genotypic variability
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Seed samples were collected from wild populations ofCapsella bursa-pastoris along a transsect from Northern to Southern Europe. Progeny was grown in (a) open-field random block experiments (47 populations) and (b) in growth chambers under five to seven controlled temperature regimes (18 populations). Beginning of flowering was recorded, and great differences between and also within populations are documented. Some populations are extremely heterogenous whereas others are homogenous in this respect. Some biotypes react positively when exposed to lower temperatures, others are inhibited. In many cases specific effects of day- and/or night-temperatures can be inferred. In some progenies begin of flowering is independent of temperature as long as this exceeds the 5:10°C regimen. Altogether,Capsella bursa-pastoris displays definite intraspecific variation in time required until flowering. Adaptations to local ecological conditions are obvious. In addition to a genotypic component pronounced environmental interactions provide the plants with a component of phenotypic plasticity. The degree of modificability apparently varies itself and seems to be controlled by selection; the phenotypic plasticity, therefore, displays adaptive variation patterns, too.
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    Plant systematics and evolution 153 (1986), S. 265-279 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cruciferae (= Brassicaceae) ; Capsella bursapastoris ; C. rubella ; C. grandiflora ; Adaptation ; growth form parameters ; phenotypic and genotypic variability
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Growth form parameters ofCapsella bursa-pastoris populations, including a wide range of different environments, have been analyzed from random block field and growth chamber experiments. Changes in one character are often correlated with changes in another. Of special interest are correlations detected with the onset of first flowering. Variation in each of the characters is clearly influenced by both phenotypic and genotypic components. However, genotype — environment interactions are also subject to variation. Therefore, the adaptive significance of a given parameter is not found to be constant over the entire geographical range of the genus. Alpine populations tend to shift from annual to biannual life cycles.
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  • 50
    ISSN: 1615-6102
    Keywords: Actin ; Adaptation ; Chara rhizoids ; Gravitropism ; Microfilaments ; Polarity ; Statoliths
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    Notes: Summary The actin cytoskeleton is involved in the positioning of statoliths in tip growingChara rhizoids. The balance between the acropetally acting gravity force and the basipetally acting net out-come of cytoskeletal force results in the dynamically stable position of the statoliths 10–30 μm above the cell tip. A change of the direction and/or the amount of one of these forces in a vertically growing rhizoid results in a dislocation of statoliths. Centrifugation was used as a tool to study the characteristics of the interaction between statoliths and microfilaments (MFs). Acropetal and basipetal accelerations up to 6.5 g were applied with the newly constructed slow-rotating-centrifuge-microscope (NIZEMI). Higher accelerations were applied by means of a conventional centrifuge, namely acropetally 10–200 g and basipetally 10–70 g. During acropetal accelerations (1.4–6 g), statoliths were displaced to a new stable position nearer to the cell vertex (12–6.5 μm distance to the apical cell wall, respectively), but they did not sediment on the apical cell wall. The original position of the statoliths was reestablished within 30 s after centrifugation. Sedimentation of statoliths and reduction of the growth rates of the rhizoids were observed during acropetal accelerations higher than 50 g. When not only the amount but also the direction of the acceleration were changed in comparison to the natural condition, i.e., during basipetal accelerations (1.0–6.5 g), statoliths were displaced into the subapical zone (up to 90 μm distance to the apical cell wall); after 15–20 min the retransport of statoliths to the apex against the direction of acceleration started. Finally, the natural position in the tip was reestablished against the direction of continuous centrifugation. Retransport was observed during accelerations up to 70 g. Under the 1 g condition that followed the retransported statoliths showed an up to 5-fold increase in sedimentation time onto the lateral cell wall when placed horizontally. During basipetal centrifugations ⩾ 70 g all statoliths entered the basal vacuolar part of the rhizoid where they were cotransported in the streaming cytoplasm. It is concluded that the MF system is able to adapt to higher mass accelerations and that the MF system of the polarly growing rhizoid is polarly organized.
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    Plant ecology 29 (1975), S. 199-208 
    ISSN: 1573-5052
    Keywords: Adaptation ; Ecological diversity ; Evolutionary strategies ; Fire ; Mediterranean region ; Regeneration ; Rootsprouters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Il est admis que le feu a joué un rôle décisif dans l'évolution biologique et culturale de l'époque postglaciaire dans la région méditerranéenne. Son impact sur l'évolution des plantes s'est manifesté par des réponses de ‘rétroaction’ (feedback). Dans celles-ci, les effets de l'élément feu et de ses répercussions ont effectué une sélection des plantes pour certaines activitées physiologiques et autres mécanismes, ce qui entraîne une tolérance directe au feu ou une protection et une régénération par voie végétative et reproductrice. Les phanérophytes dominants du maquis, sclérophylles, tolérants à la sécheresse, présentent obligatoirement des rejets de souche, alors que les chaméphytes dominés fuyant la sécheresse aussi bien que les plantes herbacées vivaces se multiplient à la fois par voie végétative et reproductrice, et sont bien adaptés aux nouvelles habitats dénudés par les feux. Les herbes annuelles et vivaces qui suivent le passage des feux sont aussi capables d'échapper aux températures élevées des feux grâce à des mécanismes de torsion, oudes graines. Les tendances évolutives pour surmonter l'effet du feu sont étroitement liées à celles d'autres ‘contraintes’ (stresses) de l'environnement comme la sécheresse et la pression du pâturage. Certaines combinaisons des contraites ont entraîné une convergence de forme et de fonction. Le feu a donc joué un rôle important dans l'évolution des pelouses plus xériques, des forêts, des maquis plus mésiques et des communautés d'arbustes. Contrairement au point de vue actuel sur le rôle destructeur du brûlage, le feu et le pâturage ont favorisé la diversité génétique aussi bien qu'écologique. Ils devraient être étudiés comme des composantes intégrantes des écosystèmes de Méditerranée et de leur évolution.
    Notes: Summary Fire has played a decisive role in Post-Glacial biological and cultural evolution in the Mediterranean Region. Its evolutionary impact on plants has been manifested by feedback responses, in which the fire and its after-effects selected plants for physiological and other mechanisms that enable direct fire tolerance or permit avoidance followed by vegetative and reproductive regeneration. The dominant, sclerophyll, drought-tolerant phanerophytes of the maqui are obligatory rootsprouters, whereas the subordinate, drought-evading chamaephytes, as well as herbaceous perennials, are both vegetative and reproductive regenerators and are well adapted to new, fire-denuded habitats. Annual and perennial grass fire-followers are also able to escape high surface fire temperatures with the aid of torsion devices on seeds. Evolutionary strategies to overcome fire are closely interwoven with those against other environmental stresses such as drought and grazing. These combinations of stresses have brought about convergence in plant form and function in mediterranean climates. Fire has thus been important in the evolution of more xeric grasslands and woodlands and more mesic maqui and shrubland communities. Contrary to the present view of fire as simply destructive, both fire and grazing have favored genetical as well as ecological diversity. They should be studied as integral components of Mediterranean ecosystems and their evolution.
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  • 52
    ISSN: 1573-5052
    Keywords: Adaptation ; Ammophila ; Genetic differentiation and phenotypic flexibility ; Perennial ; Puccinellia
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    Topics: Biology
    Notes: Abstract Perennial species invading the early stages of primary successions face constant, and often rapid, change in their biotic and abiotic environment. The relative abilities of different species to adapt to this change is reflected in the zonation patterns which characterize coastal vegetation. Variation in those species with wide ecological amplitudes, particularly in populations near the boundary of the realized niche, is likely to be particularly revealing. The pattern of heritable variation in Puccinellia maritima on salt marshes indicates directional selection for traits increasing plant vigour and ‘competitive ability’; presumably the effect of increasing plant density. Adaptation is by both genetic differentiation and phenotypic flexibility, the former being evident in adjacent grazed and ungrazed marshes and the latter in a mosaic of tall and short vegetation types. By contrast variation in Ammophila arenaria on dunes exhibits high levels of phenotypic flexibility, growth in a range of environments indicating that plants from fore-dune populations are higher ‘responders’ than those from mature dunes. Among the implications of these results, and by comparison with other species, is the fact that, ironically, niche expansion for some salt marsh perennials may require the evolution of an annual strategy, and that a Darwinian selection model may help to explain variation in Ammophila's apparent vigour in dunes of different age.
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    Biology and philosophy 5 (1990), S. 127-148 
    ISSN: 1572-8404
    Keywords: Adaptation ; Kauffman ; graph theory
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    Topics: Biology , Philosophy
    Notes: Abstract It is shown that complex adaptations are best modelled as discrete processes represented on directed weighted graphs. Such a representation captures the idea that problems of adaptation in evolutionary biology are problems in a discrete space, something that the conventional representations using continuous adaptive landscapes does not. Further, this representation allows the utilization of well-known algorithms for the computation of several biologically interesting results such as the accessibility of one allele from another by a specified number of point mutations, the accessibility of alleles at a local maximum of fitness, the accessibility of the allele with the globally maximum fitness, etc. A reduction of a model due to Kauffman and Levin to such a representation is explicitly carried out and it is shown how this reduction clarifies the biological questions that are of interest.
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    Biology and philosophy 8 (1993), S. 409-421 
    ISSN: 1572-8404
    Keywords: Adaptation ; Darwin ; final cause ; natural selection ; plant sexuality ; teleology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract It is often claimed that one of Darwin's chief accomplishments was to provide biology with a non-teleological explanation of adaptation. A number of Darwin's closest associates, however, and Darwin himself, did not see it that way. In order to assess whether Darwin's version of evolutionary theory does or does not employ teleological explanation, two of his botanical studies are examined. The result of this examination is that Darwin sees selection explanations of adaptations as teleological explanations. The confusion in the nineteenth century about Darwin's attitude to teleology is argued to be a result of Darwin's teleological explanations not conforming to either of the dominant philosophical justifications of teleology at that time. Darwin's explanatory practices conform well, however, to recent defenses of the teleological character of selection explanations.
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    Biology and philosophy 9 (1994), S. 493-495 
    ISSN: 1572-8404
    Keywords: Adaptation ; Darwin ; final cause ; Ghiselin ; natural selection ; plant sexuality ; teleology
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    Topics: Biology , Philosophy
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    Plant ecology 68 (1986), S. 19-31 
    ISSN: 1573-5052
    Keywords: Adaptation ; Canary Islands ; Convergence ; Desert ; Morphology ; Multivariate analysis ; Vegetation structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Quantitative data on the morphology of leaves and canopy in a high elevation desert stand on Tenerife have been analyzed by multivariate methods. The results show a trend in morphological variation that is related to plant height. An interpretation of this trend in terms of the adaptive values of different character combinations suggests that this could be related to a vertical microclimatic gradient. Three main groups of species have been identified, which have evolved different adaptive strategies to different niches within a single stand. The functional values of the character combinations of each species group are discussed.
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    Cytotechnology 15 (1994), S. 87-94 
    ISSN: 1573-0778
    Keywords: Adaptation ; ammonia ; cell culture ; glutamine ; glutamate ; dipeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Although glutamine is used as a major substrate for the growth of mammalian cells in culture, it suffers from some disadvantages. Glutamine is deaminated through storage or by cellular metabolism, leading to the formation of ammonia which can result in growth inhibition. Non-ammoniagenic alternatives to glutamine have been investigated in an attempt to develop strategies for obtaining improved cell yields for ammonia sensitive cell lines. Glutamate is a suitable substitute for glutamine in some culture systems. A period of adaptation to glutamate is required during which the activity of glutamine synthetase and the rate of transport of glutamate both increase. The cell yield increases when the ammonia accumulation is decreased following culture supplementation with glutamate rather than glutamine. However some cell lines fail to adapt to growth in glutamate and this may be due to a low efficiency transport system. The glutamine-based dipeptides, ala-gln and gly-gln can substitute for glutamine in cultures of antibody-secreting hybridomas. The accumulation of ammonia in these cultures is less and cell yields in dipeptide-based media may be improved compared to glutamine-based controls. In murine hybridomas, a higher concentration of gly-gln is required to obtain comparable cell growth to ala-gln or gln-based cultures. This is attributed to a requirement for dipeptide hydrolysis catalyzed by an enzyme with higher affinity for ala-gln than gly-gln.
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    Plant ecology 89 (1990), S. 165-171 
    ISSN: 1573-5052
    Keywords: Adaptation ; Beginning of flowering ; Brassicaceae ; Genotype-environment-interaction ; Mountain ecology ; Phenotypical variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seed samples were collected from wild populations of Capsella bursa-pastoris growing along a cline from low elevations to the high mountain region in Switzerland and from different latitudes in Scandinavia. Progeny were grown in open-field random block experiments, in transplantation experiments and in growth chambers. Beginning of flowering was recorded. Under various environmental conditions we got rough ecotypic complexes: Early flowering Scandinavian populations and late flowering populations from the Alps. A quantitative promotion in a larger photoperiod exists in all populations (quantitative LTP). Along various considered altitude gradients in the Alps populations from higher elevations are later flowering and tend to overwinter (biennial). Obviously there exists a very distinct adaptation in graduate ecotypical differentiation. But geographical and climatical adaptation could be superimposed by local human influences like agriculture. The physiological and genetical background is present, but until now nearly invisible.
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    Bulletin of experimental biology and medicine 82 (1976), S. 1119-1121 
    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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    Primates 26 (1985), S. 73-84 
    ISSN: 0032-8332
    Keywords: Toothcomb ; Lemuriforms ; Adapids ; Grooming ; Phylogeny ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Debate over the original adaptive significance of the lemuriform toothcomb, whether it was principally a grooming organ or a scraper-feeding tool, currently hinges upon the functional morphology of the lower incisors and canines of lemurs and lorises, and the fossil adapids thought to be their ancestors or structural prototypes. We suggest that the morphology of the upper incisors and the oronasal complex of the latter, given the context of a more general theory of incisor evolution within the primates, exhibits preadaptive conditions foreshadowing the emergence of the toothcomb and also evidence of strepsirhine monophyly. We find in all underived lemuriforms and in most fossil adapids where the elements are known, a striking continuity in upper incisor form, including such derived features as an interincisal diastema, strong central incisor prong, low-crowned morphology and reduced premaxillary size. The pattern suggests a basic strepsirhine reduction in the functional significance of the anterior dentition in feeding and harvesting roles. These features may be related to a novel connection of the rhinarium with the vomeronasal organ via a sulcate pair of labial folds, which serves as a component of a specialized behavioral-physiological complex dealing with olfactory communication. Rather than being the anatomical nucleus of this system, the toothcomb may have been added secondarily in the lemuriform descendants of the preadapted adapids, possibly as a device to stimulate glandular secretion of pheromones by direct pressure, and to simultaneously distribute odorants through the fur.
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    Protoplasma 99 (1979), S. 99-115 
    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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  • 62
    ISSN: 1617-4623
    Keywords: Cell differentiation ; G protein ; Adaptation ; STE50 ; Yeast
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    Topics: Biology
    Notes: Summary A new gene, STE50, which plays an essential role in cell differentiation in Saccharomyces cerevisiae was detected and analysed. STE50 expression is not cell type-specific and its expression in MAT a and MATα cells is unaffected by pheromones. When present on a high copy number plasmid, STE50 causes supersensitivity to α-pheromone, and increases the level of α-pheromone-induced transcription of FUS1 in haploid a cells. Mutants bearing either of the two gene disruptions, ste50-1 or ste50-2, are sterile and have a modulated sensitivity to α-pheromone. The overexpression of STE4 (Gβ) in wild-type cells elicits a constitutive growth arrest signal, however this phenotype is suppressed by a C-terminal truncation mutation in STE50 (ste50-2). In contrast, the constitutive activation of the pheromone response pathway caused by disruption of GPA1 (Gα) is not suppressed in ste50-2 mutants. The ste50-2 mutation partially suppresses the desensitisation defect of the sst2-1 mutation, and the resulting ste50-2 sst2-1 mutants restore fertility. Our result sindicate that the ste50-2 mutant may have a defect in adaptation (hyperadaptation), and suggest a possible interaction of STE50-2 with the Gα subunit of the G protein.
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    Journal of plant research 106 (1993), S. 37-45 
    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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  • 64
    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.
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  • 65
    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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  • 66
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    Environmental biology of fishes 36 (1993), S. 73-81 
    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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  • 67
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    Environmental biology of fishes 33 (1992), S. 153-165 
    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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  • 68
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    Environmental biology of fishes 22 (1988), S. 241-247 
    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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  • 69
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    Plant and soil 90 (1986), S. 73-92 
    ISSN: 1573-5036
    Keywords: Adaptation ; N2-fixing bacteria ; Plant residues ; Populations ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Physiology and genetics of non-symbiotic N2-fixing bacteria have made much progress in recent years, especially in the case of a few reference strains. Nevertheless, understanding the ecology of diazotrophs cannot be achieved by studying only laboratory microorganisms. It is necessary to study naturally-occurring populations, to characterize their densities, size, composition, variability and variations in order to understand how a plant can select a rhizosphere population from a soil population. Very few comparisons of phenotypic diversity and dominant phenotypes in these two habitats have been made up to now. More studies of this type would allow a better knowledge of the selective pressures which actually drive the shift of population and they would permit investigation of the underlying mechanisms. These can vary from mere metabolic adaptation to selection of pre-adapted genotypes. A third mechanism is possible in which ‘pre-adapted’ genes are maintained in soil populations at very low frequencies and energy costs, and whose transfer is triggered by the selective factor to which they constitute an adaptation.
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  • 70
    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.
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  • 71
    ISSN: 1573-5036
    Keywords: Adaptation ; Carbon balance ; Carbon dioxide ; Environmental stress ; Heat stress ; Maintenance respiration ; Nitrogen fixation ; Salinity stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The fitter of two species that use different strategies to overcome the same stress may be the one that expends the least resources to cope with this stress. However, this concept has proven difficult to quantify. It is proposed here that the increase in maintenance respiration in response to stress factors such as high temperature, salinity or a high-oxygen atmosphere (one indirect effect of which is nitrogen deficiency) may provide a measure of the cost of adaptation, in terms of expenditure of assimilated carbon. A corrolary to this is that, where it can be shown that an adaptive strategy results in the expenditure of assimilates, adaptation may be enhanced by increasing carbon assimilation. Results are presented supporting the hypothesis and its corrolary.
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  • 72
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    Environmental biology of fishes 38 (1993), S. 345-368 
    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.
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  • 73
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    Medical & biological engineering & computing 25 (1987), S. 347-349 
    ISSN: 1741-0444
    Keywords: Adaptation ; Electromagnetic energy ; Penetration ; Power transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 74
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    Annals of biomedical engineering 21 (1993), S. 501-508 
    ISSN: 1573-9686
    Keywords: Respiration ; Muscular exercise ; Associative learning ; Hebbian synapse ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract An adaptive neural network model that exhibits the optimality and homeostasis characteristics of the respiratory control system is described. Based upon the Hopfield network structure and a postulated Hebb-like respiratory synapse with correlational short-term potentiation, the model is capable of mimicking the normal ventilatory responses to exercise and CO2 inputs without the need for an explicit exercise stimulus. Results suggest the possibility of an adaptive neuronal mechanism that effects optimal homeostatic regulation of respiration in mammals.
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  • 75
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    Journal of chemical ecology 16 (1990), S. 773-790 
    ISSN: 1573-1561
    Keywords: Adaptation ; chemoreception ; electroantennogram ; European corn borer ; Lepidoptera ; Ostrinia nubilalis ; Pyralidae ; sex pheromone ; genetic strains ; 11-tetradecen-1-ol acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Experiments were conducted to (1) determine whether the electroantennogram (EAG) can detect differences among the responses of antennae from males derived from the three strains ofOstrinia nubilalis (Hübner), and (2) characterize the EAG responses of each strain to isomeric forms of the natural pheromone, (E)- and (Z)-11-tetradecen-1-ol acetate (TDA), and analogs possessing differences in the terminal alkyl group, cyclopropyl (CPA), ortert-butyl (TBA). EAG responses differed among the strains in two ways: (1) Antennae fromZZ males always produced an EAG to (Z)-TDA with an extended duration of response. This “signature” EAG response was found to be unique to the antennal response ofZZ males to (Z)-TDA, thus providing a relatively easy method of distinguishing liveZZ males fromEE orZE males. Correlated with this longer EAG response was a longer disadaptation time, i.e., the EAG response ofZZ antennae disadapted more slowly (ca. 10 min) than the response ofEE antennae. (2) Strain differences in the relative EAG amplitudes to isomers and analogs were observed at the stimulus amounts eliciting the peak EAG amplitude as follows: TDA ≥ CPA 〉 TBA forZZ males and both isomers; TDA 〉 CPA ≥ TBA and CPA ≥ TDA 〉 TBA forEE males and theE andZ isomers, respectively; CPA 〉 TBA ≥ TDA forZE males and both isomers. Dose—response relationships were seen for all compounds if amplitude (“peak height”) of the EAG was used as a measure of response. However, if width of the EAG at half the peak height (“peak width”) was used, then only theZZ antennal response to (Z)-TDA resulted in a meaningful dose-response relationship. For all strains, the EAG amplitudes elicited by theZ isomers of any of the tested compounds were greater than those elicited by the correspondingE isomers. Therefore, correlations between the relative EAG and upwind flight responses were observed in theZZ (r = 0.86) andZE (r = 0.80) strains but were not correlated in theEE strain (r = 0.18). Temporal studies showed that adaptation, not postexcision deterioration, was responsible for the observed decreases in the EAG amplitude after repetitive stimulation or after stimulation with amounts in a descending order. Disa-daptation required at least 20 min for a moderate dose (10 μg for 1 sec). Developmental studies showed that antennae from 2-day-old adults had the greatest EAG response.
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