The effect of selection on genealogies Journal Article

Author(s): Barton, Nicholas H; Etheridge, Alison M
Article Title: The effect of selection on genealogies
Abstract: The coalescent process can describe the effects of selection at linked loci only if selection is so strong that genotype frequencies evolve deterministically. Here, we develop methods proposed by Kaplan, Darden, and Hudson to find the effects of weak selection. We show that the overall effect is given by an extension to Price's equation: the change in properties such as moments of coalescence times is equal to the covariance between those properties and the fitness of the sample of genes. The distribution of coalescence times differs substantially between allelic classes, even in the absence of selection. However, the average coalescence time between randomly chosen genes is insensitive to the current allele frequency and is affected significantly by purifying selection only if deleterious mutations are common and selection is strong (i.e., the product of population size and selection coefficient, Ns > 3). Balancing selection increases mean coalescence times, but the effect becomes large only when mutation rates between allelic classes are low and when selection is extremely strong. Our analysis supports previous simulations that show that selection has surprisingly little effect on genealogies. Moreover, small fluctuations in allele frequency due to random drift can greatly reduce any such effects. This will make it difficult to detect the action of selection from neutral variation alone.
Journal Title: Genetics
Volume: 166
Issue 2
ISSN: 0016-6731
Publisher: Genetics Society of America  
Date Published: 2004-02-01
Start Page: 1115
End Page: 1131
DOI: 10.1534/genetics.166.2.1115
Open access: no
IST Austria Authors
  1. Nick Barton
    252 Barton
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