Genetic draft, selective interference, and population genetics of rapid adaptation

TL;DR

This paper reviews how rapid adaptation and genetic draft influence genetic diversity, emphasizing the need for new models like multiple-merger coalescents to better understand evolution in such populations.

Contribution

It discusses recent advances in modeling evolution under rapid adaptation, highlighting the importance of genetic draft and proposing coalescent models suited for these scenarios.

Findings

Genetic diversity depends weakly on population size in rapidly adapting populations.

Multiple-merger coalescents are more appropriate than Kingman's coalescent for these populations.

Genetic draft plays a dominant role over genetic drift in shaping diversity.

Abstract

To learn about the past from a sample of genomic sequences, one needs to understand how evolutionary processes shape genetic diversity. Most population genetic inference is based on frameworks assuming adaptive evolution is rare. But if positive selection operates on many loci simultaneously, as has recently been suggested for many species including animals such as flies, a different approach is necessary. In this review, I discuss recent progress in characterizing and understanding evolution in rapidly adapting populations where random associations of mutations with genetic backgrounds of different fitness, i.e., genetic draft, dominate over genetic drift. As a result, neutral genetic diversity depends weakly on population size, but strongly on the rate of adaptation or more generally the variance in fitness. Coalescent processes with multiple mergers, rather than Kingman's coalescent, are appropriate genealogical models for rapidly adapting populations with important implications for population genetic inference.