Originally published as Genetics Published Articles Ahead of Print on May 11, 2009.

Genetics, Vol. 182, 813-837, July 2009, Copyright © 2009
doi:10.1534/genetics.109.102368

The Genealogical Consequences of Fecundity Variance Polymorphism

Jesse E. Taylor1

Department of Statistics, University of Oxford, Oxford OX1 3TG, United Kingdom

1 Address for correspondence: Department of Statistics, University of Oxford, 1 S. Parks Rd., Oxford OX1 3TG, United Kingdom.
E-mail: jtaylor{at}stats.ox.ac.uk

The genealogical consequences of within-generation fecundity variance polymorphism are studied using coalescent processes structured by genetic backgrounds. I show that these processes have three distinctive features. The first is that the coalescent rates within backgrounds are not jointly proportional to the infinitesimal variance, but instead depend only on the frequencies and traits of genotypes containing each allele. Second, the coalescent processes at unlinked loci are correlated with the genealogy at the selected locus; i.e., fecundity variance polymorphism has a genomewide impact on genealogies. Third, in diploid models, there are infinitely many combinations of fecundity distributions that have the same diffusion approximation but distinct coalescent processes; i.e., in this class of models, ancestral processes and allele frequency dynamics are not in one-to-one correspondence. Similar properties are expected to hold in models that allow for heritable variation in other traits that affect the coalescent effective population size, such as sex ratio or fecundity and survival schedules.