Estimating the genome-wide contribution of selection to temporal allele frequency change

Abstract

Significance: A long-standing problem in evolutionary biology is to understand the processes that shape the genetic composition of populations. In a population without migration, two processes that change allele frequencies are selection, which increases beneficial alleles and removes deleterious ones, and genetic drift, which randomly changes frequencies as some parents contribute more or fewer alleles to the next generation. Previous efforts to disentangle these processes have used genomic samples from a single time point and models of how selection affects neighboring sites (linked selection). Here, we use genomic data taken through time to quantify contributions of selection and drift to genome-wide frequency changes. We show that selection acts over short timescales in three evolve-and-resequence studies and has a sizable genome-wide impact.