PLoS Biology (Dec 2022)
Rapid and predictable genome evolution across three hybrid ant populations
Abstract
Hybridization is frequent in the wild but it is unclear when admixture events lead to predictable outcomes and if so, at what timescale. We show that selection led to correlated sorting of genetic variation rapidly after admixture in 3 hybrid Formica aquilonia × F. polyctena ant populations. Removal of ancestry from the species with the lowest effective population size happened in all populations, consistent with purging of deleterious load. This process was modulated by recombination rate variation and the density of functional sites. Moreover, haplotypes with signatures of positive selection in either species were more likely to fix in hybrids. These mechanisms led to mosaic genomes with comparable ancestry proportions. Our work demonstrates predictable evolution over short timescales after admixture in nature. Hybridization between species is frequent in the wild but it is unclear when admixture events lead to predictable outcomes and if so, at what timescale. This study shows that selection contributes to correlated sorting of genetic variation across three independent hybrid wood ant populations in less than 50 generations.