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Author: Paula E. Marquardt
Publisher:
ISBN:
Category : Biodiversity
Languages : en
Pages : 308
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Book Description
Author: Gideon S. Bradburd
Publisher:
ISBN: 9781339260402
Category :
Languages : en
Pages :
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Book Description
Genetic variation provides the raw materials for both local adaptation and the formation of new species, and understanding the processes generating and maintaining the diversity of living organisms is a fundamental aim across all areas and levels of biological research. The central question that motivated this dissertation research is: what are the patterns of variation within and between populations and species, and what processes, ecological and evolutionary, are generating those patterns? My dissertation is focused on developing statistical methods to infer and visualize spatial patterns of genetic differentiation, and provide clues about the processes that have generated them. In my first chapter, I develop a statistical method to quantify the relative contributions of ecological and geographic distance to patterns of genetic differentiation. The method, BEDASSLE, models the allele frequencies in a set of populations at a set of unlinked loci as spatially correlated Gaussian processes, in which the covariance structure is a decreasing function of both geographic and ecological distance. In my second chapter, I discuss the conceptual framework of Isolation by Environment (IBE, as opposed to Isolation by Distance, or IBD) in a review and synthesis. This work clearly defines IBE as a pattern, rather than a process, and details the different processes that can generate a pattern of IBE. In my third chapter, I extend the statistical framework developed in the first chapter to quantify signals of IBD and IBE to a general method for inferring and visualizing patterns of population structure. This method, SpaceMix, infers, for a set of sequenced samples, a map in which the distances between population locations reflect genetic, rather than geographic, proximity. Together, these chapters represent an advance in the conceptual and statistical framework for analyzing spatial patterns of population genetic structure across landscapes.
Author: Paula E. Marquardt
Publisher:
ISBN:
Category : Biodiversity
Languages : en
Pages : 308
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Book Description
Author: Bryan K. Epperson
Publisher: Princeton University Press
ISBN: 1400835623
Category : Science
Languages : en
Pages : 376
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Book Description
Population genetics has made great strides in applying statistical analysis and mathematical modeling to understand how genes mutate and spread through populations over time. But real populations also live in space. Streams, mountains, and other geographic features often divide populations, limit migration, or otherwise influence gene flow. This book rigorously examines the processes that determine geographic patterns of genetic variation, providing a comprehensive guide to their study and interpretation. Geographical Genetics has a unique focus on the mathematical relationships of spatial statistical measures of patterns to stochastic processes. It also develops the probability and distribution theory of various spatial statistics for analysis of population genetic data, detailing exact methods for using various spatial features to make precise inferences about migration, natural selection, and other dynamic forces. The book also reviews the experimental literature on the types of spatial patterns of genetic variation found within and among populations. And it makes an unprecedented strong connection between observed measures of spatial patterns and those predicted theoretically. Along the way, it introduces readers to the mathematics of spatial statistics, applications to specific population genetic systems, and the relationship between the mathematics of space-time processes and the formal theory of geographical genetics. Written by a leading authority, this is the first comprehensive treatment of geographical genetics. It is a much-needed guide to the theory, techniques, and applications of a field that will play an increasingly important role in population biology and ecology.
Author: Alisa Sedghifar
Publisher:
ISBN: 9781339542515
Category :
Languages : en
Pages :
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Book Description
Spatial patterns of genetic variation are shaped by a variety of population genetic processes, and can therefore be a rich source of information about population history. The work presented here focuses on two drivers of spatial variation: recent secondary contact after isolation, and responses to spatially varying selection. The first chapter describes expected genome-wide patterns of coancestry resulting from secondary contact between two differentiated populations, with the continuous movement of individuals by diffusive local migration. Using analytic expressions derived for expected linkage disequilibrium (LD), an inference framework was developed to estimate the timing of secondary contact and gene flow. This was applied to genomic data from spatially distributed admixed human populations, providing an alternative to commonly used admixture models. The following chapters examine patterns of spatial variation that are influenced by selection. While continued gene flow acts to homogenize allele frequencies between different populations, differential selection across space can maintain consistent patterns of geographic variation. These patterns are historically well studied, especially in the context of local adaptation. Here, genome-wide patterns of geographic variation in D. simulans is described, in order to better understand the process of local adaptation in this species, and in Drosophlia in general. Chapter two compares and contrasts patterns of differentiation between pairs of northern and southern populations of D. simulans in Australia and North America, with a focus on patterns of convergence and parallelism. There is evidence for parallel differentiation between the two continents in regions of the genome associated with regulation of gene expression. Contrary to patterns observed in the closely related Drosophila melanogaster, the spatial distribution of genetic variation in D. simulans does not support temperate adaptation outside of the species ancestral range. The results of this study suggest that populations on the two continents may have experienced independent, and different, adaptive trajectories, and that there may be limited power to detect parallel differentiation from comparing pairs of populations. Following the results of chapter two, chapter three presents a more detailed examination of genetic variation in D. simulans collected along the North American east coast and Central America. By analyzing patterns of genetic variation in 8 North American and one Panamanian population, this study identifies genetic variants that are associated with environmental gradients along the sampled transect. This study finds some evidence for the potential role of gene regulation in local adaptation, and significant overlap with D. melanogaster of genes containing latitudinally associated alleles. This study also reveals geographically inconsistent patterns of genetic variation along the cline, highlighting the need for further sampling, both temporally and geographically, in order to obtain a better understanding of population dynamics and adaptation in this species. (Gene lists and Gene Ontology enrichments for chapter 3 are available online as Supplemental file 1 and Supplemental file 2).
Author: Bryan K. Epperson
Publisher: Princeton University Press
ISBN: 0691086699
Category : Mathematics
Languages : en
Pages : 372
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Book Description
Population genetics has made great strides in applying statistical analysis and mathematical modeling to understand how genes mutate and spread through populations over time. But real populations also live in space. Streams, mountains, and other geographic features often divide populations, limit migration, or otherwise influence gene flow. This book rigorously examines the processes that determine geographic patterns of genetic variation, providing a comprehensive guide to their study and interpretation. Geographical Genetics has a unique focus on the mathematical relationships of spatial statistical measures of patterns to stochastic processes. It also develops the probability and distribution theory of various spatial statistics for analysis of population genetic data, detailing exact methods for using various spatial features to make precise inferences about migration, natural selection, and other dynamic forces. The book also reviews the experimental literature on the types of spatial patterns of genetic variation found within and among populations. And it makes an unprecedented strong connection between observed measures of spatial patterns and those predicted theoretically. Along the way, it introduces readers to the mathematics of spatial statistics, applications to specific population genetic systems, and the relationship between the mathematics of space-time processes and the formal theory of geographical genetics. Written by a leading authority, this is the first comprehensive treatment of geographical genetics. It is a much-needed guide to the theory, techniques, and applications of a field that will play an increasingly important role in population biology and ecology.
Author: Rafael Maia
Publisher: BoD – Books on Demand
ISBN: 1789857775
Category : Medical
Languages : en
Pages : 72
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Book Description
Population genetics is the basis of evolutionary studies, and has been widely used in several researches. This recent field of science has important applications for the management of populations (natural and domesticated), as well as for evolutionary studies of the various factors that affect gene frequencies over time and spatial distribution.In this work, presented in three sections (Population and Quantitative Genetics, Genetic Diversity in Crop Management, Population Genetics for Conservation Studies), the reader will find cutting-edge information in carefully selected and revised works.This book is intended for all researchers, academics, and students who are interested in the intriguing area of population genetics.
Author: Anthony Einfeldt
Publisher:
ISBN:
Category : Evolution (Biology)
Languages : en
Pages : 155
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Book Description
The movement of individuals and their genes across geographic space influences a species’ ecology and evolution, but it is often not possible to observe past or present movement directly. Molecular tools provide a means of inferring past movement and contemporary barriers to movement, because the known modes of mutation and inheritance underlying genetic variation provide clear predictions for patterns arising from movement and subdivision. In this thesis, I investigate how contemporary and historic patterns of movement shape evolutionary trajectories by investigating distributions of genetic variation in focal intertidal invertebrates of the North Atlantic. To determine how movement is affected by the interaction of currents with life-history traits, I sequenced mitochondrial and nuclear DNA of the intertidal amphipod Corophium volutator from discrete patches of mudflat habitat throughout the Northwest Atlantic. I detected patterns of genetic subdivision and gene flow concordant with hydrological patterns, demonstrating that currents shape evolution by determining dispersal pathways and cause fine-scale subdivision in marine communities. To test how C. valuator colonized the Northwest Atlantic coast, I investigated spatial genetic variation in populations from across its entire range using the same markers. I found that diversity in Northwest Atlantic populations was subsampled from more genetically diverse populations in the Northeast Atlantic, consistent with historic human-mediated introduction from the Northeast to the Northwest. To investigate how human-mediated dispersal affects species’ evolutionary trajectories, I characterized genomic variation in C. volutator and a co-occurring annelid Hediste diversicolor in populations from the Northeast and Northwest Atlantic coasts. I found extensive genetic divergence between the introduced and native ranges and genetic patterns consistent with historic admixture between populations within each range, providing evidence that human-mediated movement can create new allopatric lineages and erase ancestral genetic structure by promoting gene flow between otherwise isolated populations. Together, my results suggest that the increasing reach, magnitude, and frequency of global human movement will change the evolutionary trajectories of species associated with human vectors of transport. While contemporary connectivity will continue to be affected by regional processes (such as currents), uncurbed human activity will likely disrupt diversification arising from barriers at regional scales while promoting the formation of new lineages at a global scale.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309184746
Category : Science
Languages : en
Pages : 101
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Book Description
This book assesses the scientific value and merit of research on human genetic differencesâ€"including a collection of DNA samples that represents the whole of human genetic diversityâ€"and the ethical, organizational, and policy issues surrounding such research. Evaluating Human Genetic Diversity discusses the potential uses of such collection, such as providing insight into human evolution and origins and serving as a springboard for important medical research. It also addresses issues of confidentiality and individual privacy for participants in genetic diversity research studies.
Author: Richard Frankham
Publisher: Oxford University Press
ISBN: 0198783396
Category : Biodiversity
Languages : en
Pages : 426
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Book Description
One of the greatest unmet challenges in conservation biology is the genetic management of fragmented populations of threatened animal and plant species. More than a million small, isolated, population fragments of threatened species are likely suffering inbreeding depression and loss of evolutionary potential, resulting in elevated extinction risks. Although these effects can often be reversed by re-establishing gene flow between population fragments, managers very rarely do this. On the contrary, genetic methods are used mainly to document genetic differentiation among populations, with most studies concluding that genetically differentiated populations should be managed separately, thereby isolating them yet further and dooming many to eventual extinction Many small population fragments are going extinct principally for genetic reasons. Although the rapidly advancing field of molecular genetics is continually providing new tools to measure the extent of population fragmentation and its genetic consequences, adequate guidance on how to use these data for effective conservation is still lacking. This accessible, authoritative text is aimed at senior undergraduate and graduate students interested in conservation biology, conservation genetics, and wildlife management. It will also be of particular relevance to conservation practitioners and natural resource managers, as well as a broader academic audience of conservation biologists and evolutionary ecologists.
Author: Tong H. Joh
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 188
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Book Description
The study of the genomic regulation of catecholamine-related enzymes is a new field, emerging from the rapid advances in molecular neurobiology. This text offers detailed summaries of recent progress from the work of leading researchers in molecular genetics and enzymes. It concentrates primarily on the rate- limiting enzyme tyrosine hydroxylase, with several chapters devoted to its complex chemistry, plus an evolutionary view of its structural similarity to certain aromatic amino acid hydroxylases. The book covers the remaining three pathway enzymes and all other enzymes related to catecholamine genes.
