SummaryWe identify a fixed species difference in the relative concentrations of the cuticular hydrocarbons 2-methyl hexacosane and 5,9-pentacosadiene in Drosophilapseudoobscura and D. persimilis, and determine its genetic basis. In backcross males, this difference is due to genes on both the X and second chromosomes, while the other two major chromosomes have no effect. In backcross females, only the second chromosome has a significant effect on hydrocarbon phenotype, but dominant genes on the X chromosome could also be involved. These results differ in two respects from previous studies of Drosophila cuticular hydrocarbons: strong epistasis is observed between the chromosomes that producethe hydrocarbon difference in males, and the difference is apparently unrelated to the strong sexual isolation observed between these species.
A shift to shorter cuticular hydrocarbons accompanies sexual isolation among
Drosophila americana
group populations
