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Results 401 - 450 of 990
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Blinman Eric - - 2008
Modern concerns with climate change often overlook the extensive history of both climate change and human adaptation over the millennia. While questions of human-climate system causation are important, especially to the extent that our current behavior is driving environmental change, human societies have experienced multiple climate changes in the past, ...
Oorebeek Margot - - 2009
Ticks are extremely susceptible to desiccation when not on a host. Even though Ixodid ticks are capable of surviving extreme conditions, it is in the best interest of the tick to locate a host quickly. The aim of this study was to determine the host stimuli used by larval Ixodes ...
Braendle Christian - - 2008
Many developmental processes generate invariant phenotypes in a wide range of ecological conditions. Such robustness to environmental variation is a fundamental biological property, yet its extent, limits, and adaptive significance have rarely been assessed empirically. Here we tested how environmental variation affects vulval formation in Caenorhabditis nematodes. In different environments, ...
Srikantha Thyagarajan - - 2008
Candida glabrata undergoes reversible, high-frequency core switching between phenotypes that include dark brown (DB), light brown (LB) and white (Wh). These phenotypes in turn can switch to the irregular wrinkle (IWr) phenotype. Natural isolates, however, express predominantly the DB phenotype, leading to the hypothesis that it has a colonization advantage ...
Tomanek Lars - - 2008
Physiological processes that set an organism's thermal limits are in part determining recent shifts in biogeographic distribution ranges due to global climate change. Several characteristics of the heat-shock response (HSR), such as the onset, maximal, and upper limit of heat-shock protein (Hsp) synthesis, contribute to setting the acute upper thermal ...
Kishimoto-Yamada K - - 2009
In Southeast Asian tropical rainforests, two events, severe droughts associated with the El Niño-Southern Oscillation and general flowering, a type of community-wide mass flowering, occur at irregular, supra-annual intervals. The relationship between these two supra-annual events and patterns of insect population fluctuations has yet to be clearly elucidated. Leaf beetles ...
Dunlap Paul V - - 2008
Many marine fish harbor luminous bacteria as bioluminescent symbionts. Despite the diversity, abundance, and ecological importance of these fish and their apparent dependence on luminous bacteria for survival and reproduction, little is known about developmental and microbiological events surrounding the inception of their symbioses. To gain insight on these issues, ...
McCauley Edward - - 2008
A long-standing issue in ecology is reconciling the apparent stability of many populations with robust predictions of large-amplitude population cycles from general theory on consumer-resource interactions. Even when consumers are decoupled from dynamic resources, large-amplitude cycles can theoretically emerge from delayed feedback processes found in many consumers. Here we show ...
Ayers Jessica M - - 2009
There are two principal strategies for managing climate change risks: mitigation and adaptation. Until recently, mitigation and adaptation have been considered separately in both climate change science and policy. Mitigation has been treated as an issue for developed countries, which hold the greatest responsibility for climate change, while adaptation is ...
Monahan William B - - 2008
Our ability to accurately forecast species' geographical responses to climate change requires knowledge of the proximate and ultimate drivers of their distribution. Here, we consider the ecophysiological and demographic determinants of the distribution of a partial migrant, the North American field sparrow, Spizella pusilla. From 1940 to 1963, the field ...
Gómez José M - - 2008
An adaptive role of corolla shape has been often asserted without an empirical demonstration of how natural selection acts on this trait. In generalist plants, in which flowers are visited by diverse pollinator fauna that commonly vary spatially, detecting pollinator-mediated selection on corolla shape is even more difficult. In this ...
van Hoof Thomas B - - 2008
Complementary to measurements in Antarctic ice cores, stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of preindustrial atmospheric CO(2) concentration. CO(2) trends based on leaf remains of Quercus robur (English oak) from the Netherlands support the presence of significant ...
Wolf Max - - 2008
In many animal species, individuals differ consistently in suites of correlated behaviors, comparable with human personalities. Increasing evidence suggests that one of the fundamental factors structuring personality differences is the responsiveness of individuals to environmental stimuli. Whereas some individuals tend to be highly responsive to such stimuli, others are unresponsive ...
Butlin Roger K - - 2008
The most common classification of modes of speciation begins with the spatial context in which divergence occurs: sympatric, parapatric or allopatric. This classification is unsatisfactory because it divides a continuum into discrete categories, concentrating attention on the extremes, and it subordinates other dimensions on which speciation processes vary, such as ...
Reimchen Thomas E - - 2009
Slight departures from bilateral symmetry are usually associated with reduced fitness. Here we show that an insular freshwater population of Gasterosteus aculeatus exhibits spatial and temporal segregation according to the incidence and direction of asymmetry in the number of bony lateral plates, which are important predator-defense structures. We analyzed 11,263 ...
Kent Clement - - 2008
Chemical communication mediates social interactions in insects. For the fruit fly, D. melanogaster, the chemical display is a key fitness trait because it leads to mating. An exchange of cues that resembles a dialogue between males and females is enacted by pheromones, chemical signals that pass between individual flies to ...
Vijendravarma Roshan K - - 2009
Most organisms experience strong selection to develop mechanisms to resist or tolerate their pathogens or parasites. Limits to adaptation are set by correlated responses to selection, for example reduced abilities to detect other parasites or trade-offs with other fitness components. For a few model systems it is now becoming possible ...
Lachance Joseph - - 2008
The set of possible postselection genotype frequencies in an infinite, randomly mating population is found. Geometric mean heterozygote frequency divided by geometric mean homozygote frequency equals two times the geometric mean heterozygote fitness divided by geometric mean homozygote fitness. The ratio of genotype frequencies provides a measure of genetic variation ...
Lof Marjolein E - - 2008
Animal aggregation is a general phenomenon in ecological systems. Aggregations are generally considered as an evolutionary advantageous state in which members derive the benefits of protection and mate choice, balanced by the costs of limiting resources and competition. In insects, chemical information conveyance plays an important role in finding conspecifics ...
Lemmin, U.
Records of wind, air temperature and air pressure from nine stations, situated along the shoreline of Lake Geneva, Switzerland, were analyzed for the summer period May to September. At all stations the consistent appearance of significant spectral peaks and changes in wind direction at the diurnal frequency indicates the importance ...
Afkhami Michelle E - - 2008
Vertically transmitted symbionts associate with some of the most ecologically dominant species on Earth, and their fixation has led to major evolutionary transitions (e.g., the development of mitochondria). Theory predicts that exclusive vertical transmission should favor mutualism and generate high frequencies of symbiosis in host populations. However, host populations often ...
Woodward F I - - 2008
The terrestrial biosphere is subjected to a wide range of natural climatic oscillations. Best known is the El Niño-southern oscillation (ENSO) that exerts globally extensive impacts on crops and natural vegetation. A 50-year time series of ENSO events has been analysed to determine those geographical areas that are reliably impacted ...
Angert Amy L - - 2008
Every species occupies a restricted geographic distribution, but it is unclear why natural selection at the range margin fails to increase tolerance to limiting environmental variables and thereby allow continual range expansion. Models indicate that the interplay of demographic asymmetries, dispersal, divergent natural selection, and adaptive trade-offs across spatially varying ...
Gore Mauvis A - - 2008
Despite being the second largest fish, basking sharks (Cetorhinus maximus) have been assumed to remain in discrete populations. Their known distribution encompasses temperate continental shelf areas, yet until now there has been no evidence for migration across oceans or between hemispheres. Here we present results on the tracks and behaviour ...
Venable D Lawrence - - 2008
We quantified seed dispersal in a guild of Sonoran Desert winter desert annuals at a protected natural field site in Tucson, Arizona, USA. Seed production was suppressed under shrub canopies, in the open areas between shrubs, or both by applying an herbicide prior to seed set in large, randomly assigned ...
Le Trionnaire Gaël - - 2008
Developmental biology is one of the fastest growing and fascinating research fields in life sciences. Among the wide range of embryonic development, a fundamental difference exists between organisms with sexual or asexual development. Aphids are unusual organisms which display alternative pathways of sexual and asexual development, the orientation of the ...
Koenraadt Constantianus J M - - 2008
We investigated how temporal and spatial effects confound the functional relationship between pupal and adult populations of Aedes aegypti and thus the value of pupal numbers as predictors of dengue transmission risk in Kamphaeng Phet, Thailand. We found considerable seasonal shifts in productivity of key containers. Tires contained much less ...
Bennett Matthew R MR Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, - - 2008
Natural selection dictates that cells constantly adapt to dynamically changing environments in a context-dependent manner. Gene-regulatory networks often mediate the cellular response to perturbation, and an understanding of cellular adaptation will require experimental approaches aimed at subjecting cells to a dynamic environment that mimics their natural habitat. Here we monitor ...
Han Hsieh-Cheng - - 2009
A novel technique of applying a quartz crystal microbalance (QCM) sensor to the on-line real-time detection of microbial populations is described. The pQCM sensor was fabricated by depositing di-para-xylene (parylene) over the entire surface of a QCM sensor through a chemical vapor deposition (CVD) process. An electrically insulated film of ...
Karnani Mahesh - - 2009
The ideas of the Gaia hypothesis from the 1960s are today largely included in global ecology and Earth system sciences. The interdependence between biosphere, oceans, atmosphere and geosphere is well-established by data from global monitoring. Nevertheless the theory underlying the holistic view of the homeostatic Earth has remained obscure. Here ...
Henderiks, J.
An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO>sub>2</sub>). To date, no direct proxy for past levels of pCO<sub>2</sub> exists beyond the reach of the polar ice core records. We propose a ...
Snell-Rood Emilie C - - 2008
Ecological gradients in natural and sexual selection often result in evolutionary diversification of morphological, life history, and behavioral traits. In particular, elevational changes in habitat structure and climate not only covary with intensity of sexual selection in many taxa, but may also influence evolution of mating signals. Here we examined ...
Hagen Snorre B - - 2008
Although climatic forcing has been suspected to be the most common cause of spatial population synchrony owing to the Moran effect, it has proved difficult to disentangle the impact of climate from other possible causes of synchrony based on population survey data. Nonlinear population responses to climatic variation may be ...
Bolnick Daniel I - - 2008
Disruptive selection is often assumed to be relatively rare, because it is dynamically unstable and hence should be transient. However, frequency-dependent interactions such as intraspecific competition may stabilize fitness minima and make disruptive selection more common. Such selection helps explain the maintenance of genetic variation and may even contribute to ...
Cano J M - - 2008
Sex-biased dispersal is capable of generating population structure in nonisolated populations and may affect adaptation processes when selective conditions differ among populations. Intrasexual competition for local resources and/or mating opportunities predicts a male-biased dispersal in polygynous species and a female bias in monogamous species. The patterns of sex-biased dispersal in ...
Peters Shanan E - - 2008
The causes of mass extinctions and the nature of biological selectivity during extinction events remain central questions in palaeobiology. Although many different environmental perturbations have been invoked as extinction mechanisms, it has long been recognized that fluctuations in sea level coincide with many episodes of biotic turnover. Recent work supports ...
Zu Jian - - 2008
This paper considers the coevolution of phenotypic traits in a community comprising two competitive species subject to strong Allee effects. Firstly, we investigate the ecological and evolutionary conditions that allow for continuously stable strategy under symmetric competition. Secondly, we find that evolutionary suicide is impossible when the two species undergo ...
Montarry J - - 2008
This study investigated local adaptation of Phytophthora infestans populations, the causal agent of potato late blight, to two susceptible potato cultivars, each grown for a number of years and over large areas in separate French regions. We measured aggressiveness (quantitative pathogenicity) of each pathogen population to sympatric and allopatric hosts ...
Toräng Per - - 2008
Theory predicts that, with conflicting selection pressures mediated by mutualists and antagonists, alternative reproductive strategies can be maintained by negative frequency-dependent selection if it results in rare-morph advantage. We combined field experiments and surveys of natural populations to determine whether selection on floral display is frequency dependent in the self-incompatible ...
Badyaev Alexander V - - 2008
Divergent selection on traits involved in both local adaptation and the production of mating signals can strongly facilitate population differentiation. Because of its links to foraging morphologies and cultural inheritance song of birds can contribute particularly strongly to maintenance of local adaptations. In two adjacent habitats--native Sonoran desert and urban ...
Burgess Malcolm D - - 2008
Spatial processes could play an important role in density-dependent population regulation because the disproportionate use of poor quality habitats as population size increases is widespread in animal populations-the so-called buffer effect. While the buffer effect patterns and their demographic consequences have been described in a number of wild populations, much ...
Guelinckx Jef - - 2008
Information on movement patterns of marine fishes between estuarine populations and stocks at sea is fundamental to understanding their population dynamics, life history tactics and behavior. Furthermore, understanding estuarine habitat use by marine fishes is crucial for their effective conservation and integrated estuarine management. Although large numbers of young marine ...
Charmantier Anne - - 2008
Rapid climate change has been implicated as a cause of evolution in poorly adapted populations. However, phenotypic plasticity provides the potential for organisms to respond rapidly and effectively to environmental change. Using a 47-year population study of the great tit (Parus major) in the United Kingdom, we show that individual ...
Lind Martin I - - 2008
The developmental threshold is the minimum size or condition that a developing organism must have reached in order for a life-history transition to occur. Although developmental thresholds have been observed for many organisms, inter-population variation among natural populations has not been examined. Since isolated populations can be subjected to strong ...
Benard Michael F - - 2008
Ecological and evolutionary processes are affected by forces acting at both local and regional scales, yet our understanding of how these scales interact has remained limited. These processes are fundamentally linked through individuals that develop as juveniles in one environment and then either remain in the natal habitat or disperse ...
McPeek Mark A - - 2008
Various evolutionary forces may shape the evolution of traits that influence the mating decisions of males and females. Phenotypic traits that males and females use to judge the species identify of potential mates should evolve in a punctuated fashion, changing significantly at the time of speciation but changing little between ...
Steffan-Dewenter Ingolf - - 2008
The relative importance of bottom-up or top-down forces has been mainly studied for herbivores but rarely for pollinators. Habitat fragmentation might change driving forces of population dynamics by reducing the area of resource-providing habitats, disrupting habitat connectivity, and affecting natural enemies more than their host species. We studied spatial and ...
Relethford John H - - 2008
A variety of methods have been used to make evolutionary inferences based on the spatial distribution of biological data, including reconstructing population history and detection of the geographic pattern of natural selection. This article provides an examination of geostatistical analysis, a method used widely in geology but which has not ...
Castellote Manuel - - 2008
The Ligurian-Corsican-Provencal Basin is a fin whale summer feeding ground, but little is known about the seasonal movement patterns of this population. We acoustically monitored two regions off Spain (eastern and southern) during summer-fall-winter 2006 using seafloor autonomous recording units. Long patterned sequences of 20 Hz pulses and back-beats from ...
Schwabe Christian - - 2008
Evolution is a complex problem by any standard. In an effort to fit the past events to the prevailing theory of evolution, the natural phenomenon has become so convoluted and polemic-ridden that it has floated clear out of the roam of science. This assay is an attempt to bring all ...
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