Genetics of sexual isolation in females of theDrosophila simulansspecies complex

Abstract

SummaryGenetic analysis of hybrids betweenDrosophila simulansandD. sechelliashows that sexual isolation in females is caused by at least two genes, one on each major autosome, while the X chromosome has no effect. These results are similar to those of a previous study of hybrids betweenD. simulansand another sibling species,D. mauritiana. In this latter hybridization, each arm of the second chromosome carries genes causing sexual isolation in females, implying a total divergence of at least three loci. The genetic similarity between theD. simulans/D.mauritianaandD. simulans/D.sechelliahybridizations probably results from independent evolution and not phylogenetic artifacts, because the dominance relationships and behavioural interactions differ between the two hybridizations. The lack of an X-chromosome effect on sexual isolation contrasts with genetic studies of post-zygotic reproductive isolation, which invariably show strong effects of this chromosome.