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166,610 نتائج ل "Population biology"
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Troublesome science : the misuse of genetics and genomics in understanding race
It is well established that all human beings today, wherever they live, belong to one single species. Yet even many people who claim to abhor racism take for granted that human \"races\" have a biological reality. From pharmacological researchers to the U.S. government, the dubious tradition of classifying people by race lives on. In Troublesome Science, Rob DeSalle and Ian Tattersall provide a lucid and compelling presentation of how the tools of modern biological science have been misused to sustain the belief in the biological basis of racial classification. Troublesome Science argues that taxonomy, the scientific classification of organisms, provides a cure for such misbegotten mischaracterizations. DeSalle and Tattersall explain how taxonomists do their job, in particular the genomic and morphological techniques they use to identify a species and to understand and organize the relationships among different species and the variants within them. They detail the use of genetic data to trace human origins and look at how scientists have attempted to recognize discrete populations within Homo sapiens. DeSalle and Tattersall demonstrate conclusively that these techniques, when applied correctly to the study of human variety, fail to find genuine differences, striking a blow against pseudoscientific chicanery. While the diversity that exists within our species is a real phenomenon, it nevertheless defeats any systematic attempt to recognize discrete units within it. The stark lines that humans insist on drawing between their own groups and others are nothing but a mixture of imagination and ideology.
Consumer-resource dynamics (Monographs in population biology ; 36)
Despite often violent fluctuations in nature, species extinction is rare. California red scale, a potentially devastating pest of citrus, has been suppressed for fifty years in California to extremely low yet stable densities by its controlling parasitoid. Some larch budmoth populations undergo extreme cycles; others never cycle. In Consumer-Resource Dynamics, William Murdoch, Cherie Briggs, and Roger Nisbet use these and numerous other biological examples to lay the groundwork for a unifying theory applicable to predator-prey, parasitoid-host, and other consumer-resource interactions. Throughout, the focus is on how the properties of real organisms affect population dynamics. The core of the book synthesizes and extends the authors' own models involving insect parasitoids and their hosts, and explores in depth how consumer species compete for a dynamic resource. The emerging general consumer-resource theory accounts for how consumers respond to differences among individuals in the resource population. From here the authors move to other models of consumer-resource dynamics and population dynamics in general. Consideration of empirical examples, key concepts, and a necessary review of simple models is followed by examination of spatial processes affecting dynamics, and of implications for biological control of pest organisms. The book establishes the coherence and broad applicability of consumer-resource theory and connects it to single-species dynamics. It closes by stressing the theory's value as a hierarchy of models that allows both generality and testability in the field.
Analysis of evolutionary processes
Quantitative approaches to evolutionary biology traditionally consider evolutionary change in isolation from an important pressure in natural selection: the demography of coevolving populations. In Analysis of Evolutionary Processes, Fabio Dercole and Sergio Rinaldi have written the first comprehensive book on Adaptive Dynamics (AD), a quantitative modeling approach that explicitly links evolutionary changes to demographic ones. The book shows how the so-called AD canonical equation can answer questions of paramount interest in biology, engineering, and the social sciences, especially economics. After introducing the basics of evolutionary processes and classifying available modeling approaches, Dercole and Rinaldi give a detailed presentation of the derivation of the AD canonical equation, an ordinary differential equation that focuses on evolutionary processes driven by rare and small innovations. The authors then look at important features of evolutionary dynamics as viewed through the lens of AD. They present their discovery of the first chaotic evolutionary attractor, which calls into question the common view that coevolution produces exquisitely harmonious adaptations between species. And, opening up potential new lines of research by providing the first application of AD to economics, they show how AD can explain the emergence of technological variety.
Complex Population Dynamics
Why do organisms become extremely abundant one year and then seem to disappear a few years later? Why do population outbreaks in particular species happen more or less regularly in certain locations, but only irregularly (or never at all) in other locations? Complex population dynamics have fascinated biologists for decades. By bringing together mathematical models, statistical analyses, and field experiments, this book offers a comprehensive new synthesis of the theory of population oscillations. Peter Turchin first reviews the conceptual tools that ecologists use to investigate population oscillations, introducing population modeling and the statistical analysis of time series data. He then provides an in-depth discussion of several case studies--including the larch budmoth, southern pine beetle, red grouse, voles and lemmings, snowshoe hare, and ungulates--to develop a new analysis of the mechanisms that drive population oscillations in nature. Through such work, the author argues, ecologists can develop general laws of population dynamics that will help turn ecology into a truly quantitative and predictive science. Complex Population Dynamicsintegrates theoretical and empirical studies into a major new synthesis of current knowledge about population dynamics. It is also a pioneering work that sets the course for ecology's future as a predictive science.
Population-scale sequencing reveals genetic differentiation due to local adaptation in Atlantic herring
The Atlantic herring (Clupea harengus), one of the most abundant marine fishes in the world, has historically been a critical food source in Northern Europe. It is one of the few marine species that can reproduce throughout the brackish salinity gradient of the Baltic Sea. Previous studies based on few genetic markers have revealed a conspicuous lack of genetic differentiation between geographic regions, consistent with huge population sizes and minute genetic drift. Here, we present a cost-effective genome-wide study in a species that lacks a genome sequence. We first assembled a muscle transcriptome and then aligned genomic reads to the transcripts, creating an “exome assembly,” capturing both exons and flanking sequences. We then resequenced pools of fish from a wide geographic range, including the Northeast Atlantic, as well as different regions in the Baltic Sea, aligned the reads to the exome assembly, and identified 440,817 SNPs. The great majority of SNPs showed no appreciable differences in allele frequency among populations; however, several thousand SNPs showed striking differences, some approaching fixation for different alleles. The contrast between low genetic differentiation at most loci and striking differences at others implies that the latter category primarily reflects natural selection. A simulation study confirmed that the distribution of the fixation index F ST deviated significantly from expectation for selectively neutral loci. This study provides insights concerning the population structure of an important marine fish and establishes the Atlantic herring as a model for population genetic studies of adaptation and natural selection.
Population Dynamics and Seasonal Patterns of IChironomus plumosus/I in the Shallow Lake Trasimeno, Central Italy
Field sampling of littoral macrobenthos of the shallow Lake Trasimeno was conducted along 17 years (2005–2021) on 129 different occasions. This long-term field study deepens the knowledge concerning the life cycle of Chironomus plumosus (Diptera), the main responsible for summer chironomid swarms that adversely affect human littoral activities, providing useful information for its management. About 108,000 macrobenthic specimens were collected, belonging to Oligochaeta (Naididae) (62%), Diptera (Chironomidae) (37%), and only 1.5% to other invertebrate taxa. Eighteen chironomid taxa were found. The trend of chironomid density was not affected by C. plumosus, which showed a maximum increase in September. This peak is justified by the presence of large swarms of C. plumosus in late August in which the populations of the central area of Lake Trasimeno consistently participate. The larval density of this species did not increase over the 17 years. A detailed analysis of the sampled larvae and adult biomass catches from 2017 to 2020 reveals that four annual swarmings occurred: in April, July, August, and September–October. The water temperature remains higher than 20 °C during the night hours from the end of May to mid-September, strengthening the hypothesis of the three midge swarming cycles in the summer period until early autumn.