Localization of pheromonal sexual dimorphism in Drosophila melanogaster and its effect on sexual isolation.

Drosophila melanogaster is sexually dimorphic for cuticular hydrocarbons, with males and females having strikingly different profiles of the long-chain compounds that act as contact pheromones. Gas-chromatographic analysis of sexual mosaics reveals that the sex specificity of hydrocarbons is located in the abdomen. This explains previous observations that D. melanogaster males display the strongest courtship toward mosaics with female abdomens. We also show that males of the sibling species Drosophila simulans preferentially court D. melanogaster mosaics with male abdomens. Because the primary male hydrocarbon in D. melanogaster is also the primary female hydrocarbon in D. simulans, this supports the idea that interspecific differences in cuticular hydrocarbons contribute to sexual isolation.