Sexual selection on song and cuticular hydrocarbons in two distinct populations of Drosophila montana

Sexual selection has the potential to contribute to population divergence and speciation. Most studies of sexual selection in Drosophila have concentrated on a single signaling modality, usually either courtship song or cuticular hydrocarbons (CHCs), which can act as contact pheromones. We have examined the relationship between both signal types and reproductive success using F1-3 offspring of wild-collected flies, raised in the lab. We used two populations of the Holarctic species Drosophila montana, that represent different phylogeographic clades which have been separate for ca. 0.5 MY, and which differ to some extent in both traits. Here we characterise the nature and identify the targets of sexual selection on song, CHCs and both traits combined within the populations. Three measures of courtship outcome were used as fitness proxies. They were the probability of mating, mating latency and the production of rejection song by females and showed patterns of association with different t...