polygenic adaptation
Hancock AM, Witonsky DB, Ehlera E, Alkorta-Aranburu G, Beallc C, Gebremedhind A, Sukernike R, Utermannf G, Pritchard JK, Coop G & Di Rienzo A 2010 Human adaptations to diet, subsistence, and ecoregion are due to subtle shifts in allele frequency. PNAS 107:8924-8930.
- selection acting on polygenic traits may lead to subtle shifts in allele frequency at many loci
- with each allele making a small contribution to the phenotype
- given that most phenotypic variation is polygenic, adaptations due to small changes in allele frequencies are likely to be widespread
- most human variation is shared across populations
- the same adaptive allele may often be independently selected in different geographic areas that share the same environment
- the environmental aspects considered in this analysis changed dramatically over human evolutionary time
- as a result, selection on standing—rather than new—alleles, which afford a faster adaptive response to environmental change (32), may have played a prominent role in adaptation to new environments
- selection will generate small allele frequency shifts at many loci until the population reaches a new optimum
- approaches that detect selection under a hard sweep model aim to identify loci that drove a new allele quickly to high frequency in the population
- our approach is well suited to detect small shifts in the frequencies of beneficial alleles that have a broad geographic distribution
