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Geographical Genetics (MPB-38)

Geographical Genetics (MPB-38)

Copyright Date: 2003
Pages: 376
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  • Book Info
    Geographical Genetics (MPB-38)
    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 Geneticshas 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.

    eISBN: 978-1-4008-3562-1
    Subjects: Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
  3. Preface
    (pp. xi-xiv)
  4. CHAPTER 1 Space–Time Population Genetics
    (pp. 1-10)

    Spatial patterns of genetic variation have three facets. First, spatial structure is interdependent with many population genetic processes, including microenvironmental selection, clinal selection, biparental inbreeding, and inbreeding depression. In many cases, valid models of genetic processes must include spatial context. This is true within a single population as well as in the context of a system of populations. The integral role of spatial structure of genetic variation in evolutionary processes was recognized in the formation of the neo-Darwinian synthesis. For example, when Sewall Wright (e.g., 1931) took his studies of genetics and breeding systems to the population level, his models...

  5. CHAPTER 2 Geographical Patterns Observed in Nature
    (pp. 11-42)

    What can spatial patterns reveal about population genetic processes? Variation of a species across its native range has always been central to the study of evolution, both in terms of how it ispartitionedwithin versus among populations and itsspatial pattern. Both depend strongly on the amount of migration, and natural selection wherever it may be acting. Any geographic survey of genetic variation, whether for purposes of studying evolution, ecological genetics, genotype by environmental interactions, or genetic disease, generally involves, either explicitly or implicitly, some aspects of space–time processes. Spatial patterns acquire the accumulated effects of migration and...

  6. CHAPTER 3 Ancient Events in Spatial–Temporal Processes
    (pp. 43-66)

    Major events in the distant past may leave transient signatures in spatial and spatial–temporal patterns of genetic variation. Important ancient events include the time and place of genetic “innovations,” refugia, range expansions, colonizations or major immigration events, and fragmentation. Transient effects of ancient events contrast with stable patterns that can be produced by selection, genetic drift, and migration averaged over long periods. The study of transient effects of major events in the distant past calls for a somewhat different emphasis in the context of spatial–temporal processes. For example, in the theoretical works of Malécot (e.g., 1948) the focus...

  7. CHAPTER 4 Spatial and Space–Time Statistics
    (pp. 67-113)

    A variety of statistical methods are available for measuring the degree of spatial differentiation, spatial patterns of genetic variation, and the significance of genetic variation among populations. In addition, there are various methods for cross-correlating spatial patterns of genetic variation with other factors, such as variables representing environmental conditions or environmental selection. Measures of spatial patterns are central to genetic survey data, and they have wide-ranging uses as inferential tools. In some instances the primary objective is to quantify spatial autocorrelations with the aim of determining whether the data violate the standard statistical assumption that the data elements of samples...

  8. CHAPTER 5 Theory of Genetics as Stochastic Spatial–Temporal Processes
    (pp. 114-171)

    Studies of geographic distributions of genetic variation and past geotemporal events make reference, either explicitly or implicitly, to an underlying spatial–temporal process. For example, methods for surveying population structure, to study the fitness or selective importance of particular genes, rely on the outcome of spatial–temporal processes. Linkage disequilibrium between markers and disease genes may be caused by spatial structure, and then special methods such as the transmission disequilibrium test (Spielman et al. 1993) must be used. Studies using selectively neutral markers to measure general levels of gene flow and studies tracing past founding events, migrations, and other episodic...

  9. CHAPTER 6 Synthesis: Tying Spatial Patterns among Populations to Space–Time Processes
    (pp. 172-182)

    The subjects of chapters 2–5, observed spatial patterns, spatial statistics, and space–time process theory, are interrelated and several lines of reason can be traced. Several conclusions can be made using the introduced technical terms. First and foremost, it is clear that many important subjects in evolutionary genetics, ecological genetics, conservation genetics, medical, and other aspects of human genetics imply spatial–temporal context. We may generically view studies of these subjects as attempts to parse off especially interesting aspects of space–time processes. The set of conditions under which such parsing may be done validly is nearly as complex...

  10. CHAPTER 7 Spatial Patterns Observed within Populations
    (pp. 183-243)

    Spatial structure of genetic variation largely determines the genetic dynamics and ultimate trajectories of evolution in natural populations. For example, sibling species sometimes occur sympatrically or parapatrically, and this implies that spatial differentiation of genetic variation likely is an important part of speciation. The frequent coexistence of well-defined ecotypes in close proximity indicates a complex interplay between genetic isolation and local adaptation. Spatial differentiation and isolation allow specialization while reducing the costs of reproductive isolating mechanisms. More fundamentally, spatial structure can be the primary determinant of the mating system, and together with dispersal can have a large effect on the...

  11. CHAPTER 8 Statistical Methods for Spatial Structure within Populations
    (pp. 244-287)

    Nearly all of the theory developments on spatial structure of populations are based ultimately on pairwise measures. Although a spatial pattern contains a great deal of information, it appears that much of this information is captured in pairwise measures of correlation as a function of spatial proximity, usually simply in terms of distance. Malécot’s theoretical models of isolation by distance were almost always expressed in terms of probabilities that two genes are identical by descent (e.g., Malécot 1948, 1972). Wright’s (1943, 1946) theory of isolation by distance within populations can be translated into averaged probabilities of identity by descent of...

  12. CHAPTER 9 Theory of Spatial Structure within Populations
    (pp. 288-316)

    Sewall Wright’s theory of genetic isolation by distance centered on the levels of inbreeding within groups of individuals. Gustave Malécot’s mathematical models, inspired by Wright’s work, were more general (Epperson 1999b). To understand the theory of spatial structure within populations, it is best to trace its development from the very beginning. To connect spatial statistical measures to mathematical process models, it is critical to follow precise and consistent definitions of terms and coefficients. Recent use of multiple meanings of the same terms, casual comparisons and approximations, and biased estimators can lead to confusion of estimators with theoretical coefficients. All of...

  13. CHAPTER 10 Emerging Study
    (pp. 317-328)

    For both within and among populations, the spatial patterns observed in natural populations, statistical considerations, and space–time models all point to an intimate connection of spatial patterns to the underlying space–time process. A number of important considerations trace through the steps by which spatial patterns are used for making inferences about population genetics, from the framing of evolutionary, conservation, and ecological genetic questions, through the design of sample surveys and choice of markers and statistical methods, to the choice or construction of appropriate models of the processes. If the processes have any substantial stochastic components, then usually fairly...

  14. Literature Cited
    (pp. 329-352)
  15. Index
    (pp. 353-356)
  16. Back Matter
    (pp. 357-357)