LOCALIZATION OF PHEROMONAL SEXUAL DIMORPHISM IN DROSOPHILA-MELANOGASTER AND ITS EFFECT ON SEXUAL ISOLATION

Drosophila melanogaster is sexually dimorphic for cuticular hydrocarbo ns, with males and females having strikingly different profiles of the long-chain compounds that act as contact pheromones. Gas-chromatograp hic analysis of sexual mosaics reveals that the sex specificity of hyd rocarbons is located in the abdomen. This explains previous observatio ns that D. melanogaster males display the strongest courtship toward m osaics with female abdomens. We also show that males of the sibling sp ecies Drosophila simulans preferentially court D. melanogaster mosaics with male abdomens. Because the primary male hydrocarbon in D. melano gaster is also the primary female hydrocarbon in D. simulans, this sup ports the idea that interspecific differences in cuticular hydrocarbon s contribute to sexual isolation.