Rapid evolutionary dynamics of an expanding family of meiotic drive factors and their hpRNA suppressors.

Abstract

Meiotic drivers are a class of selfish genetic elements whose existence is frequently hidden due to concomitant suppressor systems. Accordingly, we know little of their evolutionary breadth and molecular mechanisms. Here, we trace the evolution of the Dox meiotic drive system in Drosophila simulans, which affects male-female balance (sex-ratio). Dox emerged via stepwise mobilization and acquisition of multiple D. melanogaster gene segments including from protamine, which mediates compaction of sperm chromatin. Moreover, we reveal novel Dox homologs and massive amplification of Dox superfamily genes on X chromosomes of its closest sisters D. mauritiana and D. sechellia. Emergence of Dox loci is tightly associated with 359-class satellite repeats that flank de novo genomic copies. In concert, we find coordinated diversification of autosomal hairpin RNA-class siRNA loci that target subsets of Dox superfamily genes. Overall, we reveal fierce genetic arms races between meiotic drive factors and siRNA suppressors associated with recent speciation.