Migration Restores Hybrid Incompatibility Driven By Mitochondrial-Nuclear Sexual Conflict

Abstract

In the mitochondrial genome, sexual asymmetry in transmission favors mutations that are advantageous in females even if they are deleterious in males. Called the "Mother's Curse", this phenomenon induces a selective pressure for nuclear variants that compensate for this reduction in male fitness. Previous work has demonstrated not only the existence of these interactions but also their potential for acting as Dobzhansky–Muller loci. However, it is not clear how readily they would give rise to and sustain hybrid incompatibilities. Here, we use computer simulations in SLiM 3 to expand analytical theory to investigate the consequences of sexually antagonistic mitochondrial-nuclear interactions in a subdivided population. We consider distinct migration schemes and vary the chromosomal location, and consequently the transmission pattern, of nuclear restorers. Disrupting these co-evolved interactions results in less-fit males skewing the sex ratio towards females. Restoration of male fitness depends on both the chromosomal location of nuclear restorers and the migration scheme. Our results show that these interactions may act as Dobzhansky–Muller incompatibilities, but their strength is not enough to drive population isolation. Combined, this model shows the varied ways in which populations respond to migration's disruption of co-evolved mitochondrial-nuclear interactions.