246T Poster - Population Genetics
Thursday June 09, 8:30 PM - 9:15 PM

Authors:
Vivak Soni ^1,2; Adam Eyre-Walker ²; Michiel Vos ³

Affiliations:
1) ASU; 2) University of Sussex; 3) University of Exeter

Keywords:
Natural selection

The role that balancing selection plays in the maintenance of genetic diversity remains unresolved. One approach is to consider polymorphisms that are shared between populations or species. However, a major problem with this approach is differentiating selectively maintained polymorphisms from neutral variation inherited from the common ancestor. This problem can be solved by comparing the number of shared polymorphisms at sites that are selected, to those that are neutral. Here we introduce a new test, based on the McDonald-Kreitman test, in which the number of polymorphisms that are shared between populations is contrasted to those that are private at selected and neutral sites. Through simulation we show that this simple test is robust to a variety of demographic changes, and that it can also give a direct estimate of the number of shared polymorphisms that are directly maintained by balancing selection. We apply our method to population genomic data from humans and provide some evidence that hundreds of non-synonymous polymorphisms are subject to balancing selection.