SEXISOL

Lack of sexual attraction can directly cause reproductive isolation between individuals from different populations. Divergence of sexual processes between populations is therefore considered one of the most powerful drivers of speciation. However, we do not know exactly how these mechanisms of sexual isolation evolve. One plausible hypothesis is that divergent sexual selection driving sexual signals and preferences in different directions may be at the origin of sexual isolation. Here we propose to test this hypothesis in a complex of marine isopods (Jaera albifrons) in which sexual isolation results from female mate choice based on tactile courtship by males. First, we will simultaneously investigate intraspecific and interspecific sexual processes, asking if competition over mates within species drives selection on the same sexual signals that are involved in sexual isolation between species. Second, we will study the genomic patterns associated with sexual isolation, focusing particularly on the role of sex chromosomes and chromosomal rearrangements. Specifically, we will test if these genomic regions affect reproductive isolation through hybrid fitness effects of recombination arrest. We expect this project to tell us if and how sexual isolation evolves from divergent sexual selection, and improve our understanding of the specific role of sex and rearranged chromosomes in speciation.