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  • Adaptation
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  • Springer  (115)
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  • 1
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    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
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    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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    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
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    Cellular and molecular life sciences 43 (1987), S. 57-63 
    ISSN: 1420-9071
    Keywords: Climate ; health ; human bioclimatology ; meteoropathology ; geriatrics ; Mediterranean area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 5
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    Oecologia 74 (1987), S. 236-246 
    ISSN: 1432-1939
    Keywords: Plants ; 15N/14N ratios ; Climate ; Coastal ; Saline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Data are presented for the 15N/14N ratios of 140 indigenous terrestrial plants from a wide variety of natural habitats in South Africa and Namibia. Over much of the area, from high-rainfall mountains to arid deserts, the δ 15N values of plants lie typically in the range -1 to +6‰; with no evident differences between C3 plants and C4 grasses. There is a slight correlation between δ 15N and aridity, but this is less marked than the correlation between the δ 15N values of animal bones and aridity. At coastal or saline sites, however, the mean δ 15N values for plants are higher than those at nearby inland or non-saline sites-e.g.: arid Namib coast (10‰ higher than inland Namib); wet Natal beach (5‰ higher than inland Natal); saline soils 500 km from coast (4‰ higher than non-saline soils). High values were also found at one site where there were no marked coastal or saline influences. These environmental effects on the isotopic composition of plants will extend upwards to the animals and humans they support. They therefore have important consequences for the use of nitrogen isotope data in the study of the dietary habits and trophic structures of modern and prehistoric communities.
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  • 6
    ISSN: 1432-1939
    Keywords: Climate ; Clonal variation ; Community structure ; Herbivory ; Interspecific competition ; Plant-insect interactions ; Thrips
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of clonal variation, interspecific competition, and climate upon the population size of Apterothrips secticornis was assessed by a series of observations and experimental manipulations. Three clones of the host plant, Erigeron glaucus, consistently supported different numbers of thrips during monthly censuses. When rosettes of the three clones were transplanted to a common garden, relative numbers of thrips on the clones remained the same as those observed where the clones grew in situ. The presence or absence of other hervivores had no effect on thrips numbers in the common garden. Plume moth caterpillars and thrips were observed to co-occur less often than expected in the field but this was caused by differences in habitat selection by these two species rather than being the result of interspecific competition. Populations of thrips were affected by climate, but analyses suggest that the host clone was a more important factor.
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  • 7
    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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  • 8
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    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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  • 9
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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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  • 10
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    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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  • 11
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    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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  • 12
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    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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  • 13
    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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  • 14
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    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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  • 15
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    Landscape ecology 6 (1991), S. 15-27 
    ISSN: 1572-9761
    Keywords: Climate ; microclimate ; energy balance ; dunes ; dune formation ; wind ; temperature ; precipitation ; evaporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extremely important to the climate in any region are the radiation balance and the exchange processes of heat, water vapour and momentum. Most climatological parameters (e.g. temperature, humidity, wind speed, cloudiness and precipitation) are the direct or indirect result of the radiation balance and these exchange processes. The weather of the West European coast from Tarifa (Spain) to Skagen (Denmark) is especially suitable for the formation of dunes. Often a wind is blowing, varying widely in force and direction. The conditions are optimal for the formation of high and wide dune complexes, given a large supply of sand by the sea. The annual precipitation surplus is considerable for most of this coast. This favours the establishment of vegetation, and thereby it enhances dune formation. The short distance to the land-sea border causes strong gradients in several climatological parameters. These gradients lead to mesoscale effects, such as land-sea breezes and coastal fronts. The varying vegetation cover and the presence of slopes in all directions induce a strongly varying microclimate. However, this microclimate is not unique to the coastal dunes. Unique is the interaction with the wide range of ambient weather, which is inherent to the coast. It is not possible to be conclusive about the effects of climatic change on coastal dunes because climate models are not yet able to predict the changes adequately and because these models supply information on the expected mean climate, but not on the actual weather.
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  • 16
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    Pure and applied geophysics 120 (1982), S. 626-641 
    ISSN: 1420-9136
    Keywords: Climate ; Ozone ; Photochemical model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We have studied the effects on the ozone concentration and surface temperature, of perturbations in the atmospheric content of nitrous oxide, methane, carbon dioxide and chlorofluorocarbons (CFC). The sensitivity study has been carried out with a radiative-convective-photochemical model. The doubling of carbon dioxide concentration has the effect of warming the troposphere and cooling the stratosphere. As a result of this cooling, the change of ozone columnar density produced by 10 ppb of chlorine amount to 9.3% as compared to −10.9% obtained without temperature feedback. Perturbation in nitrous oxide correspond to an increase in NO x of the stratosphere with consequent ozone reduction while doubling the methane concentration correspond to a slight increase in columnar density. The effect of the increased methane concentration in the stratosphere contributes to reduce the effect of CFC due to the enhanced formation of HCl. The perturbation of these two minor constituents appreciably increase the greenhouse effect to 2.30 from 1.67°, obtained when carbon dioxide alone is considered.
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  • 17
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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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  • 18
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    Environmental geology 22 (1993), S. 178-185 
    ISSN: 1432-0495
    Keywords: River water chemistry ; Petrography ; Geomorphology ; Climate ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In the present paper the factors controlling river water chemistry are described and their significance is evaluated, including: climate, petrography, soils/sediments, geomorphology of the catchment area, hydrography, pollution, biological activity of rivers, and rainwater composition. The results of this study indicate that the dominant factors influencing riverwater chemistry are the climate and the petrography of the catchment area. In the case of heavily polluted rivers, pollution appears to be the dominant factor. The approach followed is based on the watershed information, e.g., climatic, geomorphological, petrographical (percentage distribution of geochemical important petrographic units), soil/sediment composition, rainwater composition, as well as the hydrographic and the hydrochemical data of the rivers. In order to achieve a better understanding of the nature of the factors influencing river water composition as well as to specify them quantitatively, multivariate statistical analyses (factor and cluster analyses) were performed on the rain-corrected hydrochemical and petrographic information of the watersheds.
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  • 19
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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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  • 20
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    Calcified tissue international 36 (1984), S. S118 
    ISSN: 1432-0827
    Keywords: Bone ; Strain ; Remodeling ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary For bone to remodel adaptively, the cells responsible should follow some algorithm. Nine different loading situations and structures are discussed. It seems that either algorithm must be extremely complex, or cells in different structures must follow different algorithms.
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  • 21
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    International journal of biometeorology 32 (1988), S. 33-35 
    ISSN: 1432-1254
    Keywords: Climate ; Age at menarche ; High school girls ; Environmental temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Age at menarche was studied by the recollection method in two groups of Causasian Jewish high school girls, inhabitants of two towns in Israel, Safad and Elat. The two towns differ mainly in climatic conditions. The age at menarche was found to be significantly lower (P〈0.02) in the hot town of Elat than in the temperate town of Safad: 13.30±1.21 and 13.58±0.9 years, respectively (mean ±SD). A significant association was found between the age at menarche and the town in which the girls lived. Accordingly, in the hot town of Elat, the percentage of girls who had their first menstrual cycle by the age of 12 years and earlier, was more than double that of the girls in Safad (17.9% and 7.1%, respectively). It is concluded that the environmental temperature, with or without any possible interaction of humidity, is probably responsible for the tendency for an earlier onset of menarche in girls living in the hot town of Elat.
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    International journal of biometeorology 32 (1988), S. 280-282 
    ISSN: 1432-1254
    Keywords: Climate ; Rubber ; Yield ; overwintering ; Growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract According to the author's and his collaborators' investigations, the climate influences the growth of rubber trees (Hevea brasiliensis) in Xishuangbanna, the southern part of Yunnan Province, China, in at least four aspects: (1) The yield of latex per tapping and the final yield of dry rubber per tree per year or per unit area per year; (2) the growth rate, as expressed by increment of girth in cm; (3) the survival during the over-wintering period; (4) the initiation or suppression of certain diseases; In this paper the author would like to describe the influence of climatic elements on yield of latex and on survival during the over-wintering period. As for the other two aspects, only general comments are given.
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    International journal of biometeorology 34 (1990), S. 194-203 
    ISSN: 1432-1254
    Keywords: Climate ; Classification ; Principal components analysis ; Landscape ecology ; Rhine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract An ordination and classification it carried out on the climate of the Rhine catchment based on data from meteorological stations. The objective of the classification is to provide an ecological interpretation of climate data. The climate of northern France, Belgium, Luxemburg, the Netherlands, the Federal Republic of Germany and northern Switzerland is divided into five classes, of which two, the Atlantic and the subcontinental are subdivided further into subclasses. The climate classes can be interpreted ecologically and are correlated with floristic and vegetation data. The Rhine valley has a distinctive and characteristic climate. Interpolation of the classification is not carried out, because of the uneven geographical spread of the sites in the dataset.
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    International journal of biometeorology 37 (1993), S. 113-124 
    ISSN: 1432-1254
    Keywords: History ; Climate ; Health ; Tourism ; Hippocratic corpus philosophy
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    Topics: Geography , Physics
    Notes: Abstract This paper creates a framework for the study of the history of tourism for climate and health. It traces the ways in which people have both moved away from detrimental health conditions and towards places thought to provide climatic cures. It brings to light the complex issues that have affected the course of the tourist trade. In this way it helps to explain that the modern geographical distribution of the highly fashionable resort areas of the world owe a great deal to past and present interpretations of the HippocraticCorpus.
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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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    International journal of biometeorology 36 (1992), S. 108-112 
    ISSN: 1432-1254
    Keywords: Citrus flowers ; Induction ; Israel ; Climate
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    Topics: Geography , Physics
    Notes: Abstract In this study the distribution of optimum temperatures for the induction of citrus blossoms in Israel has been determined. The number of flowers that form on citrus plants grown in the subtropics is known to be affected by the temperatures to which the plants are exposed. However, too few records of hourly temperatures exist in Israel to make an estimate of the occurrence and/or distribution of temperatures beneficial for citrus flower induction, although maximum and minimum temperatures are widely recorded. Thus, a model derived from the hourly records could be applied to the stations recording only maximum and minimum temperatures. The average optimum temperature was mapped for citrus flower induction throughout Israel.
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    Oecologia 88 (1991), S. 30-40 
    ISSN: 1432-1939
    Keywords: Alpine ecology ; CO2 ; Climate ; δ13C ; Leaf structure ; Oxygen ; Photosynthesis ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In an earlier paper we provided evidence that carbon isotope discrimination during photosynthesis of terrestrial C3 plants decreases with altitude, and it was found that this was associated with greater carboxylation efficiency at high altitudes. Changing partial pressures of CO2 and O2 and changing temperature are possible explanations, since influences of moisture and light were reduced to a minimum by selective sampling. Here we analyse plants sampled using the same criteria, but from high and low altitudes along latitudinal gradients from the equator to the polar ends of plant distribution. These data should permit separation of the pressure and temperature components (Fig. 1). Only leaves of fully sunlit, non-water-stressed, herbaceous C3 plants are compared. The survey covers pressure differences of 400 mbar (ca. 5000 m) and 78 degrees of latitude (ca 25 K of mean temperature of growth period). When habitats of similar low temperature (i.e. high altitude at low latitude and low altitude at polar latitude) are compared, discrimination increases towards the pole (with decreasing altitude and thus increasing atmospheric pressure). Latitudinally decreasing temperature at almost constant atmospheric pressure (samples from low altitude) is associated with a decrease in discrimination. So, polar low-altitude plants have δ13C values half way between humid tropical lowland and tropical alpine plants. It is unlikely that latitudinal changes of the light regime had an effect, since low and high altitude plants show contrasting latitudinal trends in δ13C although local altitudinal differences in overall light consumption were small. These results suggest that both temperature and atmospheric pressure are responsible for the altitudinal trends in 13C discrimination. Temperature effects may partly be related to increased leaf thickness (within the same leaf type) in cold environments. Theoretical considerations and laboratory experiments suggest that it is the oxygen partial pressure that is responsible for the pressure related change in discrimination. The study also provided results of practical significance for the use of carbon isotope data. Within a community of C3 plants, discrimination in species of similar life form, exposed to similar light, water and ambient CO2 conditions ranges over 4‰, with standard deviations for 10–30 species of ±0.6 to 1.2‰. This natural variation has to be taken into account by using a sufficient sample size and standardization of sampling in any attempt at ecological site characterization using carbon isotope data. Evidence of a pronounced genotypic component of this variation in 13C discrimination in wild C3 plant species is provided. Correlations with dry matter partitioning, mesophyll thickness and nitrogen content are also present.
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    Oecologia 93 (1993), S. 242-250 
    ISSN: 1432-1939
    Keywords: Climate ; Ducks ; Diversity ; Multivariate analysis ; Prairies
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    Topics: Biology
    Notes: Abstract Tramer (1969) proposed that communities regulated by competition in benign, predictable environments were characterized by (i) damped variation in evenness relative to variation in richness over time, and (ii) high evenness relative to communities regulated by variation in the abundance and diversity of resources in rigorous, unpredictable environments. To test whether patterns of variation in diversity could reflect the mechanisms proposed to regulate community structure, temporal and spatial changes in the diversity, richness and evenness of breeding duck communities were examined along a gradient of variability in wetland conditions using thirty-three years of duck census and climate data from the Canadian prairie and boreal forest regions. Temporal variation in evenness was independent of wetland habitat variability. Changes in richness were more parsimoniously explained by the appearance of ducks displaced (by drought) from rigorous, variable, wetland habitats into relatively benign ones, than by competition in benign areas. Evenness was not significantly higher for duck guilds in more constant wetland habitats, as predicted. Variation in richness, evenness and diversity, predicted by Tramer, do not provide a basis for distinguishing the factors that regulate duck community structure.
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    Oecologia 97 (1994), S. 179-185 
    ISSN: 1432-1939
    Keywords: Diapause ; Development ; Grasshopper ; Adaptation ; Geographic variation
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    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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    Oecologia 72 (1987), S. 69-76 
    ISSN: 1432-1939
    Keywords: Cabbage butterfly ; Pieris rapae ; Evolution ; Adaptation ; Colonisation
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    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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  • 31
    ISSN: 1432-1939
    Keywords: Adaptation ; Speciation ; Urine ; Kidney ; Spalax ehrenbergi
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    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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    Oecologia 76 (1988), S. 553-561 
    ISSN: 1432-1939
    Keywords: Adaptation ; Carbon isotope ratio ; Leaf conductance ; Water-use efficiency
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    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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  • 33
    ISSN: 1432-1939
    Keywords: Developmental rate ; Adult weight ; Adaptation ; Temperature ; Acyrthosiphon pisum
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    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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  • 34
    ISSN: 1432-1939
    Keywords: Adaptation ; Leaf pubescence ; Leaf reflectance ; Desert ecology
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    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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  • 35
    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 70 (1986), S. 283-287 
    ISSN: 1432-1939
    Keywords: Arianta ; Pulmonata ; Egg cannibalism ; Oophagy ; Climate
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    Topics: Biology
    Notes: Summary Factors affecting oophagy among siblings in the land snail Arianta arbustorum were studied in 3 populations from different altitudes in Switzerland. The degree of egg cannibalism in A. arbustorum is a function of hatching asynchrony since the earliest hatched snails will devour the unhatched eggs in the same clutch. Clutch size, egg density and amount of vegetable food available to newly hatched snails did not affect the degree of cannibalism. Snails from 3 populations were similar in terms of incubation time and intrinsic hatching asynchrony of the clutches. However, they differed in degree of cannibalism when the hatching asynchrony had been experimentally increased. Snails from a lowland forest showed a higher degree of cannibalism than did those from an alpine mountain slope. The parent snails differed in terms of incubation time and hatching synchrony in their clutches. Under natural conditions, the length of the hatching spread and, as a result, the degree of cannibalism will depend additionally on the mode of oviposition (batches or single; clumped or dispersed), on the spatial heterogeneity of egg-laying places and on climatic conditions (e.g. drought).
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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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    Oecologia 76 (1988), S. 273-277 
    ISSN: 1432-1939
    Keywords: Grasses ; Photosynthetic type ; Distribution ; Climate ; Altitude ; Argentina
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    Topics: Biology
    Notes: Summary The distribution of native C3 and C4 grasses in a temperate arid region of Mendoza, Argentina, was studied in six areas at different altitudes. C4 species predominate at low elevations in both relative species abundance and plant cover. At high elevations C3 species are dominant in cover and composition. At medium altitudes (1100–1600 m) grass species composition is balanced but plant cover of C3 species is greater. Of 31 genera in the whole area, 19 were C4. Only the genera Stipa (C3) and Aristida (C4) were present in all the six areas surveyed. The pattern of grass distribution shows high correlation with evapotranspiration and temperature parameters, but low correlation with rainfall. The relation between grass distribution and different climatic parameters is discussed.
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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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  • 40
    ISSN: 1432-1017
    Keywords: Receptor potential ; Intracellular and extracellular calcium concentration ; Intensity dependence ; Adaptation ; Sensitivity control
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    Topics: Biology , Physics
    Notes: Abstract The light-induced membrane voltage response (receptor potential, ReP) and the absorption change of the intracellularly injected calcium indicator arsenazo III (arsenazo response) were recorded simultaneously in Limulus ventral nerve photoreceptor cells. A double pulse technique was applied for stimulation. After pressure injection of the indicator into the cell absorption changes were measured at 646 nm to obtain a measure of the changes of the intracellular calcium ion concentration. 1. The size of the arsenazo response increases with increasing intensity of the light stimulus. The intensity dependence of the size of the arsenazo response δAmax shows almost no correlate with the peak amplitude of the ReP, but correlates rather well with the time integral of the ReP. 2. Decreasing light adaptation (caused by prolongation of the repetition time of the pulse pairs) leads to an increase in size of the arsenazo response. Also here δAmax correlates better with the time integral of the ReP than with its peak amplitude. 3. Lowering the calcium concentration in the superfusate (from 10 mmol/l to ca. 40 Μmol/l) causes after ca. 10 min a drastical diminution of the arsenazo response to values below the noise level, and a less marked reduction in size of the ReP. The falling phase of the ReP is slower. After return to normal calcium concentration the arsenazo response recovers partly in ca. 50 min, while the ReP recovers faster. The results show two opposite correlations between ReP and arsenazo response: Increase in size and duration of the ReP causes a greater transient increase of the intracellular calcium ion concentration. This in turn tends to reduce and shorten the ReP. Which effect dominates obviously depends on the conditions of the experiment: when the calcium concentration in the superfusate is reduced to ca. 40 Μmol/l a slow decrease of the ReP is accompanied by a small increase of the intracellular calcium ion concentration.
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    European biophysics journal 7 (1981), S. 205-208 
    ISSN: 1432-1017
    Keywords: Grasshopper ; Electroretinogram ; Adaptation ; Spectral sensitivity
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    Topics: Biology , Physics
    Notes: Abstract The grasshopper ERG displays a rapid recovery of responsivity following the onset of a background light. Although observed earlier in skate and frog, this phenomenon has not previously been seen in an invertebrate. Furthermore, a period of hyperresponsivity exists in early dark adaptation and resembles that found in skate and frog. Thus, recovery in the light and hyperresponsivity in the dark seem to be corollaries of each other. Finally, spectral sensitivity of the ERG is determined and two peaks are found: one at 510 nm and the other at 360 nm. The former appears to be a rhodopsin-mediated sensitivity but the latter does not and they are not clearly separated by chromatic adaptation.
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  • 42
    ISSN: 1432-1017
    Keywords: Photoreceptor ; Visual pigment ; Adaptation ; Facilitation
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    Topics: Biology , Physics
    Notes: Abstract A conditioning light can cause a decrease (adaptation) or an increase (facilitation) in the sensitivity of barnacle photoreceptors, as measured by the amplitude of the late receptor potential (LRP). We show that a net transfer of visual pigment from the rhodopsin (R) to the metarhodopsin (M) state induces a large facilitation whereas the reverse transfer results in a much smaller facilitation or even an adaptation. These effects were not due to the response to the conditioning light but to the pigment reactions. When the conditioning light did not alter the pigment population (i.e., M → M, R → R) it was followed by an intermediate degree of facilitation. These conclusions are correct for cells which have relatively low sensitivity. In sensitive cells, all pigment transitions produce adaptation. LRP facilitation and the prolonged depolarizing afterpotential (PDA) show several common characteristics with respect to pigment transitions: 1.Their magnitude increases with the amount of pigment transferred from R to M. 2. Both are depressed by the M → R transition. 3. Their production is impeded by the M → R transition. 4. The PDA itself is facilitated by the R → M transition and this facilitation decays with a time course comparable to that of LRP facilitation. These results suggest that there may be an underlying process common to LRP facilitation and PDA.
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    European biophysics journal 8 (1982), S. 173-187 
    ISSN: 1432-1017
    Keywords: Leech photoreceptors ; Extracellular calcium ; Excitation ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Extracellular recordings from the vacoule of photoreceptor cells of Hirudo medicinalis L. were performed using microelectrodes. The cells were adapted by white light flashes given at constant intervals (20 s). Response height versus relative intensity curves obtained from the same cell in physiological saline (PS) and in bathing solutions of either a) lowered calcium contents (2 ΜM/1 or less) or b) raised calcium contents (15 mM/1) were compared. The cells' adaptation state in PS was operationally defined by the ratio Q=h A /h S where h A is the response height evoked by the adapting flashes, and h S is the corresponding saturation response height. Sensitivity changes were measured by the half saturation intensity shift. Lowering extracellular calcium resulted in: 1. The response height increased and the shape of the response became more rounded and prolonged. 2. The total resistance between the vacuole and outside decreased from 8.2±1.4 MΩ (n=6) in PS to 4.6±0.4 MΩ (n=5). The resistance was independent of the cells' adaptation state. 3. A change of the cells' sensitivity occured either in direction to light adaptation or in direction to dark adaptation. It depended functionally on the ratio Q: a) if Q was less or equal to about 0.6 the cells' sensitivity increased. b) if Q was greater than 0.6 the cells' sensitivity diminished. Raising extracellular calcium decreased the sensitivity of all cells tested independent of their adaptation states in PS. The results can be interpreted under the assumptions that 1. the sensitivity of leech photoreceptor cells is inversely proportional to the intracellular free calcium concentration and Z. intracellular calcium can interact with extracellular calcium in relatively dark adapted cells whereas in relatively light adapted cells the raise of intracellular free calcium is mainly effected by a release from intracellular stores. It is assumed that a Q value of about 0.6 separates relatively light adapted cells from relatively dark adapted cells.
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  • 44
    ISSN: 1432-0983
    Keywords: Chromosome length variants ; Adaptation ; Yeast ; Continuous culture
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    Topics: Biology
    Notes: Summary Thirteen independent populations of Saccharomyces cerevisiae (nine haploid and four diploid) were maintained in continuous culture for up to approximately 1000 generations, with growth limited by the concentration of organic phosphates in medium buffered at pH 6. Analysis of clones isolated from these populations showed that a number (17) of large-scale chromosomallength variants and rearrangements were present in the populations at their termination. Nine of the 16 yeast chromosomes were involved in such changes. Few of the changes could be explained by copy-number increases in the structural loci for acid phosphatase. Several considerations concerning the nature and frequency of the chromosome-length variants observed lead us to conclude that they are selectively advantageous.
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    Environmental management 13 (1989), S. 789-795 
    ISSN: 1432-1009
    Keywords: Climate ; General circulation models ; Regional analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The climate simulations from atmospheric general circulation models (GCMs) are often used to analyze the potential effects of climate change on environmental resources. It has been demonstrated that there are differences among the simulations from various GCMs, on spatial scales ranging from global to regional. This paper quantifies the differences in temperature and precipitation simulated by three major GCMs for four specific regions: an agricultural region (the North American winter wheat belt), a hydrologic region (the Great Basin), a demographic region (the high-density population corridor of the northeast United States), and a political region (the state of Texas). Both the current (control) climate and the climatic response to a doubling of atmospheric carbon dioxide (CO2) are considered In each region, even when the data are averaged on a seasonal basis, marked differences occurred in the areal average climate simulated by the different GCMs for both the control climate and the doubled-CO2 climate. Thus, climate impact studies based on the simulations of more than one GCM could easily yield a range of possible results
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    Journal of comparative physiology 168 (1991), S. 151-157 
    ISSN: 1432-1351
    Keywords: Adaptation ; Information ; Unifying theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Concepts from information theory can enhance our understanding of perceptual processes by providing a unified picture of the process of perception. A single equation is shown to embrace adaptation phenomena, stimulus-response relations, and differential thresholds. Sensory adaptation is regarded as representing a gain in information by the receptor. It is calculated that for constant stimuli in the form of step inputs, insects and arachnids obtain approximately the same amount of information per stimulus from their respective environments as do human beings.
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    Archives of microbiology 147 (1987), S. 117-120 
    ISSN: 1432-072X
    Keywords: Adaptation ; Ciliate ; Stentor coeruleus ; Photophobic response ; Action spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of preillumination on photophobic response (light-adaptation) and recovery of the photophobic sensitivity in the dark (dark-adaptation) in Stentor coeruleus were examined. When the cells were preilluminated with white light of 7.80 W/m2 for 2 min, the fluence-rate response curve of photophobic response was shifted toward higher light intensities by half an order of magnitude compared to the one without preillumination. Preillumination with a higher light intensity resulted in a further shift of the fluencerate response curve. An action spectrum for light-adaptation showed a primary peak at 610 nm and secondary peaks at 540 and 480 nm which are almost identical to the peaks observed in the photophobic action spectrum. The light-adapted cells showed a recovery of their photophobic sensing ability following dark treatment. Dark-adaptation resulted in total recovery of photophobic sensing ability in 8 minutes for the most cases examined.
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    Archives of microbiology 129 (1981), S. 127-128 
    ISSN: 1432-072X
    Keywords: Continuous culture ; Adaptation ; Simulation of hot springs ; Boiling point ; Caldoactive bacteria
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    Topics: Biology
    Notes: Abstract Bacillus caldolyticus, a caldoactive bacterium originating from a hot spring at Yellowstone Park, was grown in a defined medium, whose composition resembled that of the pool water. Using a chemostat culture, which simulated the natural conditions, the organism could be adapted to grow at 100°C at a reasonable rate. Under increased pressure growth occurred also at 105° C.
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    Archives of microbiology 130 (1981), S. 159-164 
    ISSN: 1432-072X
    Keywords: Adaptation ; Boiling point ; Caldoactive enzymes ; Stabilization ; Thermostability ; Thermal characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In chemostat cultures of Bacillus caldolyticus, adaptation in a single step from 70–100°C was followed under aerobic and oxygen-limited conditions and was found to proceed more smoothly under the latter circumstances. Variations of the medium (e.g. yeast extract or silicate concentrations) showed that growth at 100°C is in all respects similar to that of cultures at moderate temperatures. Enzyme preparations derived from cultures at 5°C intervals between 70 and 100°C were used to determine the temperature range. For all nine enzymes tested, the optimum temperature was found to be 67°C; the latter was independent of the growth temperature. Differences were found, however, with respect to the maximum temperature of individual enzymes, and three groups, with maxima between 70 and 80°C, 80 and 90°C and 90 and 100°C can be distinguished. Again, there was no correlation with the growth temperature. Stability experiments also revealed that enzymes from the same organism can have different thermal properties: Some were found to be quite thermolabile (e.g. the pyruvate kinase), while others (e.g. hexokinase and glutamate-pyruvate transaminase) exhibited a high thermostability. These properties were not related to the growth temperature within the 70–100°C range, too. Six of the enzymes tested could be stabilized by their respective substrates, but the degree of protection varied for individual enzymes. Three enzymes (acetate kinase, glutamate dehydrogenase and myokinase) could not be stabilized by their substrates. Comparative experiments with the hexokinase suggested, that the thermal integrity of the enzymes is better protected within the cell as compared to the stability of the enzyme preparations.
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    Archives of microbiology 131 (1982), S. 184-190 
    ISSN: 1432-072X
    Keywords: Dunaliella primolecta ; Malotolerant ; Adaptation ; Plasma membrane ; ESR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electron spin resonance spectroscopy was used to monitor the in vivo microviscosity of the plasma membrane and lipid extracts of the salt tolerant alga, Dunaliella primolecta. The fluidity of the plasma membrane decreased as the algae were adapted to and suspended in higher sodium chloride concentrations [2–24% (w/v)]. Both biochemical modification and a physical interaction between Na+ and lipids were implicated. When the microviscosity of the plasma membrane and that of lipid extracts were determined as a function of temperature, two or three lipid phase transformations were observed. There were always transformations at 9–14° C and 39–43° C. These were interpreted as the onset and completion of the lipid phase transition of at least a major lipid component of the membrane, possibly the entire membrane. These transformation temperatures were independent of the salt concentration to which the algae were adapted or suspended. This suggests that D. primolecta exists with some of its membrane in the solid-fluid mixed lipid state. With a NaCl concentration of 8% (w/v) or greater in the growth medium, a third transformation occurred around 20–22° C. It was the result of a lipid-lipid interaction and was not related to adaptation.
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  • 51
    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Adaptation ; Photosynthesis ; Carbohydrate accumulation ; Relative growth rate ; [Light-phosphate] interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Oscillatoria agardhii was grown in continuous culture under various light conditions in order to study the interactions of light on phosphorus-limited growth. Under severe P-limiting (light-saturating) conditions, a low chlorophyll a and C-phycocyanin content was found. In addition, the light-harvesting capacity, reflected in the values of P max (maximum light-saturated oxygen production rate) and α (photosynthetic affinity), were low compared to light-limited cultures. Reduction of the light climate, either by reduction of the length of the photoperiod or light-intensity, resulted in an increase in light-harvesting capacity (higher pigment content, P m and α) during growth under P-limiting conditions. Light-induced changes in P max and α could be related to the relative growth rate, being the actual growth rate as a fraction of the growth rate which would be observed under light-limiting conditions. Under P-limiting conditions, reduction of the light-climate caused a reduction in dry weight of the culture. This decrease was mainly due to a decrease in carbohydrate content of the cells. Under all conditions tested, carbohydrates were found to accumulate during the light-period and to be consumed during the dark-period. Evaluation of carbohydrate consumption in the dark yielded a specific maintenance rate constant of 0.001 h-1. This observation leads to the conclusion that the specific maintenance rate constant is independent on the character of the growth rate limiting nutrient for O. agardhii.
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    Archives of microbiology 134 (1983), S. 204-207 
    ISSN: 1432-072X
    Keywords: Photosensory ; Cations ; pH ; Flagellated ; Algae ; Adaptation ; Euglena gracilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Euglena were cultured under 3 W m-2 constant white light. In culture medium, cells show immediate and long lasting step-down photophobic responses and photoaccumulation behavior to blue light if dim red light-adapted for 30 min. However, if cells are suspended in buffered, saltcontaining solutions (adaptation buffers), strong step-down photobehavior and photoaccumulation responses are not observed for several hours. These behaviors gradually increase in strength to reach a maximum after 6–12 h; after which a stable response is maintained. The relative rates of appearance and the relative strengths of the responses are influenced by the concentrations of Ca2+ and K+, but not H+ or Na+ ions, in the adaptation buffers. Expression of the stepdown photobehavior thus requires that the cells adapt to the chemical environment in which they are suspended.
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  • 53
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Synechocystis 6701 ; Phycobilisomes ; Ultra-violet ; Mutagenesis ; Assembly ; Chromatic ; Adaptation ; Rods ; Cores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutations affecting pigmentation of the cyanobacterium Synechocystis sp. 6701 were induced with ultraviolet light. Two mutants with phycobilisome structural changes were selected for structural studies. One mutant, UV08, was defective in chromatic adaptation and incorporated phycoerythrin into phycobilisomes in white or red light at a level typical of growth in green light. The other mutant, UV16, was defective in phycobilisome assembly: little phycocyanin was made and none was attached to the phycobilisome cores. The cores were completely free of any rod substructures and contained the major core peptides plus the 27,000 Mr linker peptide that attaches rods to the core. Micrographs of the core particles established their structural details. Phycoerythrin in UV 16 was assembled into rod structures that were not associated with core material or phycocyanin. The 30,500 Mr and 31,500 Mr linker peptides were present in the phycoerythrin rods with the 30,500 Mr protein as the major component. Phycobilisome assembly in vivo is discussed in light of this unusual mutant.
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    Archives of microbiology 140 (1984), S. 96-100 
    ISSN: 1432-072X
    Keywords: Physiology ; Adaptation ; Growth ; Droop ; Monod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In many experimental ecological studies on phytoplankton species the growth response of an organism to the prevailing environmental conditions have been studied. Curves relating specific growth rate (μ) to the external nutrient concentration (S) have been constructed to compare nutrient-limited growth of different species under steady state conditions. Microorganisms adapt their physiology to a certain limitation in order to optimize growth. Therefore the shape of the μ/S curve is closely related to the way a micoorganism adapts its physiology. To see how physiological adaptation and growth rate are interconnected to each other, both can be related to the internal concentration of the growth-limiting nutrient. How the growth rate is related to the internal nutrient concentration is presented in a mathematical equation. Many phytoplankton species during growth under different nutrient limitations show a linear relationship between μ and the reciprocal value of the internal nutrient content (= Yield). This was originally observed by Droop. The model presented here gives a theoretical explanation of this phenomenon.
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  • 55
    ISSN: 1432-2285
    Keywords: Adaptation ; Leaf distribution ; Mono-layer ; Multi-layer ; Understory tree species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationships between the amounts of foliage and heights of trees were studied for the dominant understory tree species, including three evergreen and three deciduous species, in a secondary forest of Chamaecyparis obtusa Endl. The relationships showed two phases: leaf increasing and stationary phases. In the leaf-increasing phase, the height growth allowed these species to expand the canopy by increasing the number of leaves. In the stationary phase, the number of leaves was relatively constant number irrespective of tree height from 160 to 400 cm. The number of leaves in the stationary phase represents the maximum number of leaves that can be supported by trees under shady conditions. From the analyses of vertical distributions of leaves in six species, mono- and multi-layer foliage distributions were detected. Two evergreen species, Eurya japonica and Cleyera japonica, showed multi-layer foliage distributions, whereas three deciduous species, Lyonia ovalifolia, Rhododendron reticulatum and Vaccinium hirtum, and one evergreen species, Pieris japonica, showed mono-layer foliage distributions. The relationships between the weights of non-photosynthetic and photosynthetic organs of the six species were examined. The proportion of non-photosynthetic organs increased with tree height. The understory species attained the stationary phase and were maintained by minimizing their investment in non-photosynthetic organs, i.e. their height growth was arrested by the shady conditions under the crown trees.
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    Journal of comparative physiology 168 (1991), S. 393-407 
    ISSN: 1432-1351
    Keywords: Electroreception ; Descending control ; Adaptation ; Pyramidal cells ; Weakly electric fish ; Sensory processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Extracellular HRP injections into the nucleus praeeminentialis dorsalis (NPd) ofApteronotus leptorhynchus retrogradely labeled a population of elec trosensory lateral line lobe (ELL) efferent cells, deep basilar pyramidal cells, that differ morphologically from the previously described basilar and nonbasilar pyramidal cells. These neurons are found deep in the ELL cellular layers; they have small cell bodies and very short sparsely branching apical dendritic trees. The previously described basilar and nonbasilar pyramidal cells are larger, have extensive apical dendrites and are found more superficially. 2. Axon terminals of the deep basilar pyramidal cells were recorded from in the NPd and labeled with lucifer yellow. These NPd afferents have high, regular spontaneous firing rates, and respond tonically to changes in electric organ discharge amplitude. 3. Deep basilar pyramidal cell bodies were recorded from and labeled in the ELL, and these showed the same physiological responses as did the NPd afferent fibers. 4. In addition, basilar pyramidal cells were found which had spontaneous activity patterns and adaptation characteristics intermediate to those typical of the superficial basilar pyramidal cells and the deep basilar pyramidal cells. The size of the pyramidal cells' apical dendritic trees and the placement of their somata within the dorsoventral extent of the ELL cellular layers are highly correlated with the neurons' physiological properties.
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    Journal of comparative physiology 170 (1992), S. 691-700 
    ISSN: 1432-1351
    Keywords: Adaptation ; Temporal pattern ; Olfaction ; Insect ; Pheromone ; Receptor neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The temporal pattern of response in chemoreceptor neurons reflects both the temporal distribution of stimuli and the timing of signal transduction, action potential generation and propagation. Here we analyze the temporal characteristics of the responses elicited in pheromone receptor neurons by computer-controlled rectangular pulses of odorant. Extracellular recordings from the HS sensilla trichodea on the antenna of male Trichoplusia ni reveal the activity of two neurons: the “A” neuron, which responds to the major component of the female pheromone blend, (Z)7-dodecenyl acetate and the “B” neuron, which responds to (Z)7-dodecenol. “B” neurons were divided into two classes (HR, LR), based on the magnitude and temporal pattern of their response to (Z)7-dodecenol. Most “A” and HR “B” neurons responded to rectangular pulses of various durations (0.1–40 s) with an initial phasic burst (∼100 ms), followed by a slowly declining tonic component. At moderate and elevated pheromone doses, prolonged stimulation resulted in significant reductions in the tonic response levels (adaptation); stimuli of increasing duration effected greater adaptation. Most LR “B” neurons lacked a phasic response component and showed virtually no adaptation with prolonged stimulation. Pheromone receptor neurons may differ in both their spectral and temporal response properties which may provide the animal with additional sensory information for blend discrimination and spatial orientation in complex natural pheromone plumes. The potential functional value of adaptation in the moth pheromone communication system is discussed.
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    Theoretical and applied genetics 82 (1991), S. 363-367 
    ISSN: 1432-2242
    Keywords: Adaptation ; Varietal stability ; GE interactions ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Regressions of yields of cultivars upon means of sets of cultivars over diverse environments are often used as measures of stability/adaptability. Prolonged selection for performance in environments of high yield potential has generally led to unconscious selection for high regressions. If adaptation to poor environments is required (as it often is in Third World agriculture), common sense suggests that low regressions could be exploited for the purpose. Simulations show that systematic selection in the poor environment is required, not merely trials of potential cultivars after selection in a good environment. In effect, systematic exploitation of a GE interactions effect is proposed. The effects are large enough to reduce correlated responses in different environments to zero. Orderly experimental studies are needed but not available. What information there is does not disagree with the theory developed here.
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    Theoretical and applied genetics 74 (1987), S. 310-316 
    ISSN: 1432-2242
    Keywords: Stability variance ; Genotype x environment interaction ; Adaptation ; Saccharum ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stability-variance statistic, ĝs i 2 , measures the contribution of the ith genotype to genotype x environment interaction. In addition to the knowledge of cultivar stability for an agronomic trait, information on whether stability of one trait can be used to predict stability of another should be useful to breeders. Three separate groups of data, respectively involving CP 79 series, CP 80 series, and CP 81 series experimental clones of sugarcane (Saccharum spp.) were used in this study. Rank-correlation coefficients (rs) between ranks of genotypes for ĝs i 2 's for paired traits indicated in both plant-cane and ratoon crops that stability of tons per hectare of sugar can be predicted from the stability of tons per hectare of cane (THC) and also, to a lesser extent, from the stability of stalk number. The stability of THC also can be reasonably well predicted from the stability of stalk number. Brix stability may give some indication of the stabilities for percentage sucrose and sugar concentration (SC). The ĝs i 2 's for percentage sucrose and SC were almost identical in the CP 79 and CP 81 series (rs varied from 0.93, P〈0.01, in plant-cane crop for CP 79 series to 0.98, P〈0.01, in plant-cane crop for CP 81 series). Whether correlations were based on ĝs i 2 's estimated across locations within crops or across crops, the magnitude of rs was about the same. Means of various traits were not correlated with their respective ĝs i 2 's (for CP 81 series), indicating that identification and selection of high-yielding sugarcane genotypes with a relatively high degree of stability of performance across test environments should be possible.
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    Theoretical and applied genetics 88 (1994), S. 557-560 
    ISSN: 1432-2242
    Keywords: Zea mays L. ; Genome size ; Adaptation ; Nucleotype ; Agronomic performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extensive nuclear DNA content variation has been observed inZea mays. Of particular interest is the effect of this variation on the agronomic potential of maize. In the present study, yield and growth data were collected on 12 southwestern US maize open-pollinated populations. These populations, originally cultivated by the Indians of the southwestern US for both human and animal consumption and adapted to various altitudes, were grown in replicated plots at the University of Illinois Agronomy-Plant Pathology South Farm. All growth and yield parameters were found to be negatively correlated with nuclear DNA amount. The negative correlations of nuclear DNA amount and growth parameters were more pronounced at 60 days after planting (DAP) than 30 DAP. Agronomically-important yield parameters, such as ear or seed weight and seed number per plant, also exhibited a significant negative correlations with nuclear DNA amount. These correlations demonstrate how the nucleotype may exhibit a high degree of influence on the agronomic phenotype. Although the results presented here represent only three replications at one location in 1 year, the observations noted suggest that nucleotype plays an integral role in determining the agronomic performance of maize. Further studies are needed to fully document this role.
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    Theoretical and applied genetics 64 (1983), S. 133-136 
    ISSN: 1432-2242
    Keywords: Stability ; Adaptation ; Fitness trait ; Bunch yield ; Oil palm ; Elaeis guineensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary There were significant differences between hybrids for number of bunches (NB), mean bunch weight (MBW) and fresh fruit bunch yield (FFB). For the hybrid population as a whole, significant hybrid X year (environment) effects were also observed for the two yield components and for yield per se. The linear component of the hybrid X year effect was also significant. There were highly significant and positive correlations between FFB, NB and MBW hybrid means and the regression co-efficients of the hybrid means on the environmental index. There were no significant associations between these means and mean square deviations from regression (s2d) for these traits.
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    Theoretical and applied genetics 66 (1983), S. 93-99 
    ISSN: 1432-2242
    Keywords: Lactation ; Milk yield ; Herd production ; Adaptation ; Dairy cattle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eighty thousand, one hundred and eleven records of the Israeli dairy herdbook for the period of 1973–1977 were studied and examined to determine the existence of Genotype x Environment Interaction (GxE) as affecting milk yield in kg per day between calvings. Various quantitative measures of environment were used while the genotypes were evaluated as the average performance of each sire's daughters in a whole range of environments. When the environment was evaluated as level of production, the relative importance of the interaction was found to be very low. Furthermore, the linear dependence on the interaction of the individual sires with the environments was found to be inconsistent with time, meaning that no justification was found for using specific adaptation patterns of genotypes to these environments. When lactation number and given time periods were used as environments, significant interactions were found between genotypes and environments. Results of the analyses of Genotype x Lactation interaction imply that the interaction values, to a certain degree, confused the differences between the sires when based on first lactation records. We therefore conclude that the need exists to expand the basis of sire evaluation, including the addition of data on successive lactation periods beyond the first one. We maintain that the genetic characteristic for this phenomenon is the “lactations development” of a sire, i.e., the performance of its daughters during the different lactations. The “maturing rhythm” of a sire may be regarded as a dynamic expression of the genetic makeup controlling lactation development. Furthermore, the prospect of selecting sires of bulls for early or late maturing could provide a new tool for the dairy cattle breeder.
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    Theoretical and applied genetics 60 (1981), S. 145-149 
    ISSN: 1432-2242
    Keywords: Triticale ; Rye ; Hexaploids ; Adaptation ; Chromosomal substitutions ; Modified chromosomes ; Telomeric heterochromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Investigations were made on the rye chromosome constitution and on the presence of telomeric heterochromatin in rye chromosomes of the 26 most widely and 24 most narrowly adapted triticale strains. Among widely adapted lines, 22 (85%) had a complete rye genome and four triticales only had chromosomal R-D genome substitutions. Twenty-three (96%) of the 24 most narrowly adapted triticales had substitutions between the chromosomes of the R and D genomes. The most widely adapted triticales accumulated fewer modified rye chromosomes in comparison to narrowly adapted lines. They had from one to three rye chromosomes with heterochromatic deletions: 46% of widely adapted lines had two modified rye chromosomes; 34% had three modified rye chromosomes, and 19% had a single modified rye chromosome. In widely adapted strains, the 1R, 4R, 5R and 6R modified chromosomes were observed; they were present in 80%, 73%, 50% and 11% of the cases, respectively. The most narrowly adapted triticales had from two to four modified rye chromosomes: 58% of the strains had three modified rye chromosomes; 29% had four modified rye chromosomes and 12% had two modified rye chromosomes. The modified 4R and 5R chromosomes were present in all of these lines. The 1R (modified), 6R (modified) and 7R (modified) were found in 83%, 25% and 16%, respectively, of the narrowly adapted strains. Results support the previous observations (Pilch 1980b) that a wide adaptation of hexaploid triticales is associated with the presence of the full potential of rye genome, and that it is independent of the amount of telomeric heterochromatin possessed by rye chromosomes.
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    Theoretical and applied genetics 87 (1993), S. 409-415 
    ISSN: 1432-2242
    Keywords: Genotype x environment interaction ; Adaptation ; Stability ; Desirability index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The linear regression approach has been widely used for selecting high-yielding and stable genotypes targeted to several environments. The genotype mean yield and the regression coefficient of a genotype's performance on an index of environmental productivity are the two main stability parameters. Using both can often complicate the breeder's decision when comparing high-yielding, less-stable genotypes with low-yielding, stable genotypes. This study proposes to combine the mean yield and regression coefficient into a unified desirability index (D i). Thus, D i is defined as the area under the linear regression function divided by the difference between the two extreme environmental indexes. D i is equal to the mean of the i th genotype across all environments plus its slope multiplied by the mean of the environmental indexes of the two extreme environments (symmetry). Desirable genotypes are those with a large D i. For symmetric trials the desirability index depends largely on the mean yield of the genotype and for asymmetric trials the slope has an important influence on the desirability index. The use of D i was illustrated by a 20-environments maize yield trial and a 25-environments wheat yield trial. Three maize genotypes out of nine showed values of D i 's that were significantly larger than a hypothetical, stable genotype. These were considered desirable, even though two of them had slopes significantly greater than 1.0. The results obtained from ranking wheat genotypes on mean yield differ from a ranking based on D i .
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    Behavioral ecology and sociobiology 35 (1994), S. 437-443 
    ISSN: 1432-0762
    Keywords: Adaptation ; Sex ratio ; Host size ; Parasitoid wasps
    Source: Springer Online Journal Archives 1860-2000
    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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  • 66
    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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  • 67
    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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  • 68
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    Vegetation history and archaeobotany 2 (1993), S. 213-232 
    ISSN: 1617-6278
    Keywords: Human impact ; Lake Constance ; Neolithic ; Bronze Age ; Climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Archaeology , Biology
    Notes: Abstract The second part of a pollen profile from Hornstaad/Lake Constance (Germany), containing the Atlantic and Subboreal (6400 cal B.C. to 700 cal B.C.) is presented. The diagram has a sampling interval of 1 cm and an average time resolution of 10 years. The cereal curve provided the basis for cereal zones, which are used to classify the human impact. Twenty-six cereal zones can be distinguished, most of them divided into subzones, from 5500 cal B.C. to 700 cal B.C. They correspond to both known and, mostly, unknown settlements in the surrounding landscape from the Early Neolithic to the Late Bronze Age. Charcoal and chemical analyses as well as sediment accumulation, confirmed by accelerator dates, provide evidence for human impact on the environment.
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  • 69
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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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  • 70
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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
    Topics: Biology
    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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  • 71
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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
    Topics: Biology
    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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  • 72
    ISSN: 1615-6102
    Keywords: Nickel ; Endocytosis ; Motility ; Proliferation ; Cellular nickel content ; Adaptation ; Tetrahymena pyriformis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At concentrations above 1 mM, nickel has a dose-dependent effect on the rate of food vacuole formation in cells in the growth medium, proteose peptone (PP); total inhibition of endocytosis occurs within 10 minutes in 6mM nickel. However, only a 10 times lower concentration of nickel is tolerated by starved cells in an inorganic salt medium, a difference which may be ascribed to the high binding property of nickel to organic material. In the PP medium, nickel affects cell motility by increasing the rate of movement at a concentration of 1 mM, and by causing immobilization after 30 minutes in 6mM nickel; a spontaneous, partial recovery of cell motility is seen after 3 hours in 6 mM nickel. The effects of nickel on endocytosis and cell motility are reversible after removal of nickel. Cell proliferation continues at a reduced rate in 1 mM nickel, while only 1 1/2 cell doublings are achieved in 3 mM nickel during a 72-hour exposure, and no proliferation occurs in 6mM nickel, where an increasing cell mortality is observed after 12 hours. The cell content of nickel relates initially to the external concentration of the metal; however, cells in 1 mM nickel are capable of maintaining a constant content of the metal, whereas in 3 mM, the rate of accumulation is reduced after 3 hours, and cells in 6mM nickel accumulate the metal at a constant rate. All nickel-treated cells contain small refractive granules, previously proposed as representing an ion-regulating system, and the apparent adaption ofTetrahymena to the effects of nickel may be ascribed to such a regulation of the intracellular concentration of the metal.
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  • 73
    ISSN: 1615-6102
    Keywords: Actin ; Adaptation ; Chara rhizoids ; Gravitropism ; Microfilaments ; Polarity ; Statoliths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    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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  • 74
    ISSN: 1615-6102
    Keywords: Adaptation ; Light intensity ; Ligustrum ; Plastids
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    Topics: Biology
    Notes: Summary The capacity of adaptation and the range of adjustment to different light conditions in fully expanded mutant leaves were studied on an aurea variety of privet (Ligustrum ovalifolium Hassk. var.aureum). Whenever the light conditions are altered leaves respond immediately. Although adaptational changes in leaf thickness are not possible, the change in colour, as well as changes in pigment concentrations take place within several days. With increasing light intensity there is a marked decline in chlorophyll concentration and the carotenoid yield becomes much higher. Under low light conditions the chlorophyll content is high, while the carotenoid concentration drops significantly. The mutant chloroplasts from green leaves always have a well developed thylakoid system. The only difference between young green leaves (DG1) and older regreened ones (DG2) is in the number of thylakoids per granum (grana in older leaves consist of more thylakoids), while the stacking degree of thylakoids remains about the same (74 and 77% respectively). Depending on the previous light conditions fine structure of plastids in yellow leaves differs considerably. Young yellow leaves (Y0) contain plastids with longitudinal arrays of dilated thylakoids and prothylakoid bodies occasionally. Plastids from primarily green leaves which turned yellow afterwards in strong sunlight (Y1) are characterized by thylakoids densely packed into cup-shaped stacks, or large vesicles originating from dilated thylakoids. The stacking degree of thylakoids in sun exposed yellow leaves (determined only in Y0 leaves) is extremely low and reaches only 29%.
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    Plant ecology 106 (1993), S. 89-100 
    ISSN: 1573-5052
    Keywords: Climate ; Landscape islands ; Number of communities ; Number of species ; Settlement size ; Species-area relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Published data on the number of plant species and/or communities were gathered for 77 European cities and 85 villages. The relationships between the floristic and vegetation diversity and some environmental variables were analysed. Species number in cities showed log linear increase with city size (expressed as the population size or city area). A linear increase in the species number with size was found in the village flora. The richness of both city and village flora was not significantly related to any climatic variable. On the contrary, the number of communities in both villages and cities was correlated not only with settlement size but also with altitude and mean annual temperature. The diversity of village vegetation was closely related to the climax type of the respective region. The features of human settlements that make it possible to consider them as landscape islands are discussed.
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    Plant ecology 54 (1983), S. 17-25 
    ISSN: 1573-5052
    Keywords: Climate ; Distribution ; Precipitation ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of plant species and vegetation types in the Prairie provinces of Canada can be related to climatic phenomena. The ratio of summer/spring precipitation appears to be especially important, with temperatures of less importance. Climatic areas can be outlined; within these areas differences in soils are important.
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    Plant ecology 60 (1985), S. 103-111 
    ISSN: 1573-5052
    Keywords: Climate ; Discriminant analysis ; Distribution ; Formation ; Model ; North America ; Prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A discriminant model was produced that predicts North American plant formations with basic climatic variables (monthly mean temperatures, monthly precipitation, and latitude). The model is based on data from 176 weather stations. Climatic variables from 30 additional randomly-selected weather stations were used to test the model. The predicted formation and actual formation at each site were compared; four sites were classified into the wrong formations (87% accuracy). This predictive model indicates a strong correlation between climate and formations in North America. Vegetation-climate models produced by canonical discriminant analysis may be useful in detecting geographical localities where non-climatic factors are particularly influential.
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  • 78
    ISSN: 1573-5052
    Keywords: Adaptation ; Ammophila ; Genetic differentiation and phenotypic flexibility ; Perennial ; Puccinellia
    Source: Springer Online Journal Archives 1860-2000
    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
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    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 43 (1980), S. 83-86 
    ISSN: 1573-5052
    Keywords: Adaptation ; Colonization ; Environmental stochasticity ; Phenology ; Weather variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plant species co-inhabiting a given geographical region often have distinetly different times of flowering. It is shown that such phenological spread, duc to short-term stochastic variation in weather variables, relaxes competition for empty sites to be colonized by diaspores. For sufficiently large spreads stable coexistence becomes possible. The applicability of the proposed hypothesis to the observed instances of phenological spread is discussed and shown to extend beyond that of other current theories.
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    Plant ecology 53 (1983), S. 33-43 
    ISSN: 1573-5052
    Keywords: Climate ; Habitat feature ; Hejaz mountains ; Plant community ; Saudi Arabia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present study gives an assessment of the environmental factors and their effect on the pattern and distribution of the plant communities in the area along the road from Medina to Badr, Saudi Arabia. The road crosses the Hejaz mountains and the study area presents three main ecogeomorphological systems which are differentiated into various habitats. Rainfall and plant cover show wide variation, both in quantity and distribution in the different sectors of the study area. Also, the wide variations in topography, rock types and soil characteristics, have a marked influence on the water resources and consequently on the vegetation. Twenty-three communities, recognized by species dominance and habitat features, have been distinguished. These include ten communities dominated by trees and shrubs; five of them are dominated by one of the Acacia spp. growing in the area. Seven communities are dominated by suffrutescent species and six are dominated by ephemeral species. The latter communities appear only during the wet season and disappear at the beginning of summer. The floristic conoposition and the habitat features are described and the ecological relationships between the communities are briefly discussed.
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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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    Plant ecology 69 (1987), S. 189-197 
    ISSN: 1573-5052
    Keywords: Climate ; Drought ; Frost resistance ; Gap ; Life-cycle ; Plant distribution ; Population dynamics ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper investigates, with predictive models, the utility of ecophysiological responses to climate as predictors of plant distribution. At the global scale responses to extreme minimum temperatures and to the hydrological budget effectively predict the distribution limits of the major vegetation types of the World. A minimum temperature of -15°C, for example, appears critical in controlling the poleward spread of vegetation that is dominated by evergreen broadleaved species; however, the presence or absence of more frost resistant species, such as those that are deciduous broadleaved, is not obviously explained in terms of extremes of climate. In such cases, predicting the competitive relationships between species is necessary and dependent on the climatic sensitivity of population dynamics.
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    Plant ecology 76 (1988), S. 141-154 
    ISSN: 1573-5052
    Keywords: Cereal ; Climate ; Fossil pollen ; Holocene ; Palynology ; Vegetational history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The longest continuous Amazonian palynological record (ca 7010 yrs B.P. to present) from Lake Ayauchi, Ecuador, reveals species-by-species abundance changes during a period of climatic change. Pollen influx from a wet tropical rain forest was found to be high, 1×104−105 grains cm-2 yr-1, although mature forest taxa were poorly represented. Horizons of laminated sediments and weathered gyttja, dated to ca 4200–3150 B.P., evidence a period of reduced net water availability. During this period Ficus, Alchornea and Palmae pollen representation appears to decline, although there is no evidence of a major forest compositional change. The lake was reduced to a shallow, possibly seasonal, pool. Zea cultivation was recorded between ca 2850 B.P., (the earliest paleoecological record to date in the Amazon basin) and ca 800 B.P. It is suggested that Zea was cultivated on exposed lake sediment within the crater at times of low water levels. The abandonment of Zea cultivation may have been due to rising water levels or social unrest.
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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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  • 88
    ISSN: 1573-5052
    Keywords: Biomass ; Calthion palustris ; Climate ; LAI ; Microclimate ; Vegetation structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three Dutch Calthion palustris communities, situated in different phytogeographic districts which vary in elimatic conditions, are compared with respect to vegetation structure and microclimate. The three Calthion stands which are similar in soil, management and hydrology, differ slightly in total aboveground biomass in the period just before cutting, but there is a larger difference in the biomass contributed by phanerogams, bryophytes and litter. The structure of the Calthion communities varies in vertical distribution of biomass and leaf area (LAI), and growth form and leaf size composition. These differences are interpreted in terms of elimatic differences such as length of growing season, temperature and wind. Profiles of decreasing light intensity within the vegetation canopy are related to the vertical distribution of biomass, LAI and leaf inclination of the various Calthion communities. Temperature and saturation deficit of the air on the different sites show profiles of a similar shape which suggests that in such ecologically comparable plant communities, vegetation structure differs under influence of the macroclimate in such a way that the resulting vegetation canopies modify the microclimate within the vegetation to become homologous.
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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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    Plant ecology 98 (1992), S. 1-12 
    ISSN: 1573-5052
    Keywords: Climate ; Mediterranean ; Cluster analysis ; Principal Component Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Climatic data from 444 weather-recording stations in the Mediterranean basin are examined by cluster analysis and principal component analysis. The application of numerical clustering distinguished several groups of climatic stations clearly interpretable in geographic and climatic terms. The hierarchical structure of the dendrograms could be used to identify at different scales uniform climatic regions. The complementary application of principal component analysis produced an ordination of climatic types, which clearly showed the main trends of variation in the precipitation and temperature patterns.
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  • 91
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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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  • 92
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    Primates 29 (1988), S. 135-137 
    ISSN: 0032-8332
    Keywords: Papio ; Body size ; Ecology ; Climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Popp (1983) presented an intriguing argument regarding the covariation of body size in baboons and rainfall. However, a reanalysis of the data indicates that “Principle 2” of the model is not supported.
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  • 93
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    Plant systematics and evolution 143 (1983), S. 257-275 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Aegilops ; Triticum ; T. diccocoides ; wheat ; Adaptation ; trait variation ; factor analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eighteen earliness and morphological traits were examined in from 2 to 14 lines each of 10 diploid members of the wheat complex,Triticum-Aegilops, and 15 lines of the tetraploid speciesTriticum diccocoides. In general, earliness traits have the greatest relative between line vs. within line variation of all the traits examined. Within species, earliness traits are the principle set of characters around which evolve between line trait differences, one of the most important oich is leaf dimensions. At the genus level, earliness traits are independent of leaf dimensions and plant height characters. Thus, the pattern of evolution at the genus level is different from that exhibited in each of the species. Biological and evolutionary implications of these findings are discussed.
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  • 94
    ISSN: 1617-4623
    Keywords: Cell differentiation ; G protein ; Adaptation ; STE50 ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    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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  • 95
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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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  • 96
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    Plant and soil 61 (1981), S. 43-52 
    ISSN: 1573-5036
    Keywords: Adaptation ; Allelopathy ; Ecophysiology ; Grassland ; Plantago ; Nitrate production ; Nitrate reductase ; Nitrate uptake ; Nitrification ; Nitrifying bacteria ; Rhizosphere ; Root environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The production of nitrate in an old established dune grassland soil and its uptake by plants was studied by comparing amounts of mineral nitrogen and numbers of nitrifying bacteria in the rhizosphere on the one hand, and on the other accumulated nitrate and levels of nitrate reductase (NaR) of individual plants of three Plantago species,i. e., P. major, P. lanceolata andP. coronopus. For these three Plantago species andP. media basal levels of NaR in the absence of nitrate were determined in plants grown in culture solutions. The basal NaR levels ofP. major andP. media (species occurring on nutrient-rich soils) were significantly higher than those ofP. lanceolata andP. coronopus (species found on nutrient-poor soils). NaR activity increased in the presence of nitrate and was suppressed by ammonium. From the numbers of nitrifying bacteria in the rhizosphere and NaR activity in the leaves it was concluded that nitrate was produced in the root environments of the three Plantago species and that the compound was taken up by the plants. NaR activities and numbers of nitrifying bacteria were higher for individuals ofP. major than for those ofP. lanceolata andP. coronopus. No correlation was found between the ammonium levels and the numbers of nitrifying bacteria in the soil, and no indications of inhibition of nitrifying bacteria in the rhizosphere were obtained. For individuals ofP. lanceolata a correlation was found between the numbers of nitrifying bacteria in the soil and NaR activity in the leaves. The results are discussed in relation to the ecological habitats of the three species.
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  • 97
    ISSN: 1573-5036
    Keywords: Adaptation ; Luzerne ; Mutant ; Rhizobium meliloti ; Terres acides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Resume Un mutant acido-tolérant deR. meliloti a été isolé. Le caractère de résistance en milieu acide n'a pas été obtenu par adaptation sur des milieux de plus en plus acides mais par mutagenèses successives provoquées par la N-méthyl-N'nitroso-N-nitrosoguanidine (NTG) et sélection sur milieu acide de façon à rendre stable le caractère acido-tolérant. Ce mutant acide présente la propriété de se développer plus lentement que la souche sauvage sur milieu pauvre. Ceci ne l'empêche pas de présenter sensiblement la même efficience que cette dernière à pH voisin de la neutralité en milieu synthétique. L'étude comparative de l'efficience de la souche parentale et de la souche mutée sur la luzerne cultivée en terre acide est rendue difficile du fait de la présence de nitrates qui réduit la nodulation et inhibe l'action de la nitrogénase: par épuisement, en effectuant une culture dense de luzerne sur cette terre, il est possible de mettre en évidence ensuite l'activité symbiotique importante à pH 5,9 du mutant par rapport à la souche sauvage.
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  • 98
    ISSN: 1573-5036
    Keywords: Adaptation ; Adventitious roots ; Ethylene ; Flooding ; Fraxinus pennsylvanica ; Lenticels ; Turgidity ; Water potential ; Water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fraxinus pennsylvanica Marsh. seedlings that were 150 days old adapted well to flooding of soil with stagnant water for 28 days. Early stomatal closure, followed by reopening as well as hypertrophy of lenticels and formation of adventitious roots on submerged portions of stems appeared to be important adaptations for flood tolerance. Leaf water potential (ψ1) was consistently higher in flooded than in unflooded seedlings, indicating higher leaf turgidity in the former. This was the result of (1) early reduction in transpiration associated with stomatal closure, and (2) subsequently increased absorption of water by the newly-formed adventitious roots as stomata reopened and transpiration increased. Waterlogging of soil was followed by large increases in ethylene content of stems, both below and above the level of submersion. Formation of hypertrophied lenticels and adventitious roots on flooded plants was correlated with increased ethylene production. However, the involvement of various compounds other than ethylene in inducing morphological changes in flooded plants is also emphasized.
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    Plant and soil 66 (1982), S. 243-255 
    ISSN: 1573-5036
    Keywords: Adaptation ; Adventitious roots ; Ethylene ; Flooding ; Growth of seedlings ; Lenticels ; Platanus occidentalis ; Stomatal aperture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Flooding ofPlatanus occidentalis L. seedlings for up to 40 days induced several changes including early stomatal closure, greatly accelerated ethylene production by stems, formation of hypertrophied lenticels and adventitious roots on submerged portions of stems, and marked growth inhibition. Poor adaptation ofPlatanus occidentalis seedlings to soil inundation was shown in stomatal closure during the entire flooding period, inhibition of root elongation and branching, and death of roots. Some adaptation to flooding was indicated by (1) production of hypertrophied lenticels which may assist in exchange of dissolved gases in flood water and in release of toxic compounds, and (2) production of adventitious roots on stems which may increase absorption of water. These adaptations appeared to be associated with greatly stimulated ethylene production in stems of flooded plants. The greater reduction of root growth over shoot growth in flooded seedlings will result in decreased drought tolerance after the flood waters recede. The generally low tolerance to flooding of seedlings of species that are widely rated as highly flood tolerant is emphasized.
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  • 100
    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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