MBE Advance Access originally published online on September 17, 2008
Molecular Biology and Evolution 2008 25(12):2615-2626; doi:10.1093/molbev/msn209
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Research Articles |
Conditional Gene Genealogies under Strong Purifying Selection
Department of Organismic and Evolutionary Biology, Harvard University
E-mail: wakeley{at}fas.harvard.edu.
Accepted for publication September 9, 2008.
The ancestral selection graph, conditioned on the allelic types in the sample, is used to obtain a limiting gene genealogical process under strong selection. In an equilibrium, two-allele system with strong selection, neutral gene genealogies are predicted for random samples and for samples containing at most one unfavorable allele. Samples containing more than one unfavorable allele have gene genealogies that differ greatly from neutral predictions. However, they are related to neutral gene genealogies via the well-known Ewens sampling formula. Simulations show rapid convergence to limiting analytical predictions as the strength of selection increases. These results extend the idea of a soft selective sweep to deleterious alleles and have implications for the interpretation of polymorphism among disease-causing alleles in humans.
Key Words: natural selection coalescent ancestral graph Ewens sampling formula
Marcy Uyenoyama, Associate Editor