"Genetic analysis of hybridizing populations"
I intend to spend Wednesday talking about a project that I've worked
on for about a year or so. I haven't yet talked about it in Math Bio.
The abstract for the paper I submitted on it is, in part:
Biologists regularly encounter populations of organisms with
disparate ancestries. Untangling the composition of such populations
is a problem for conservation biologists and wildlife managers. In
many cases the population under question is known to consist of
individuals from two different subpopulations and their hybrids. This
occurs, for example, in hybrid zones between two species or in
regions recently colonized by exotics capable of reproducing with
resident inhabitants. This paper develops techniques using multilocus
genetic data for Bayesian clustering of individuals to purebred or
genetically-mixed categories. The method relies on a novel
application of the forward-backward recursions in a two-component,
finite mixture model. Though developed in the context of the genetic
admixture problem, these calculations are relevant more generally to
Bayesian inference in finite mixtures; they may potentially improve
mixing of the Gibbs sampler in such contexts. The technique is
applied to genetic data on the Scottish wildcat, Felis sylvestris, a
protected species whose distinctness from domestic housecats has been
questioned. A high proportion ( around 60%) of the wild-living cats
from which the sample was drawn are arguably purebred F. sylvestris.
The full manuscript is available at
http://students.washington.edu/eriq/writings/eric_anderson_JABES.pdf
On Friday I intend to talk about how I would like to extend/modify
these methods to a large dataset on steelhead/cutthroat trout hybrids
from the National Marine Fisheries Service. This is work in
progress, that with any luck, will eventually yield some results
relevant to an abstract that sounds like:
A pervasive concern in the conservation of salmonids is hybridization
between different populations and species. For example, small, wild
populations might encounter substantial gene flow from fish straying
from hatcheries. Also, the use of genetic data in helping to
delineate "evolutionarily significant units" may be complicated by
naturally-occurring hybridization between closely related species.
However, ongoing hybridization between genetically dissimilar
populations leads to predictable changes in the frequency of
multilocus genotypes, and so may be investigated using genetic marker
data. I will review recent advances in Bayesian methods for analyzing
genetic data from populations containing hybrids. I illustrate these
versatile methods by using them to estimate allele frequencies and to
identify coastal cutthroat trout, steelhead trout, and their hybrids
in samples of juvenile fish taken from Oregon and Washington.
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Eric Anderson Interdisciplinary Program in Quantitative
Ecology and Resource Management
Mailing Address: Office:
Department of Statistics Padelford Hall, C-312
University of Washington Phone:
Box 354322 (206) 685-8969 (wk)
Seattle, WA 98195 (206) 634-3204 (hm)
URL: http://students.washington.edu/eriq/