Introgression in hybrid ants is favored in females but selected against in males

Significance Hybridization in animals has commonly been considered rare. In contrast, recent studies suggest hybridization to play a central role in both speciation and adaptation. This work highlights a complex process resulting from hybridization; exchange of genomic regions between species inFormica wood ants is at the same time selected for and against, leading to an intragenomic conflict and extremely strong natural selection. The results suggest that the genomic regions acquired through hybridization harbor both incompatibilities and adaptive genetic variation. Our study has implications for the genomic architecture of speciation and argues for incorporating adaptive introgression into the current models of genomic divergence.