Behavioral reproductive isolation in the Hawaiian Drosophila, D. silvestris and D. heteroneura : are test designs interchangeable?

The planitibia group of the Hawaiian Drosophila have been instrumental in the development of the hypothesis that behavioural reproductive isolation explains past speciation events. This controversial hypothesis states that the direction of evolution can be inferred by examining the direction of behavioral reproductive isolation that entails an asymmetry of female choice of mates between closely related species. The hypothesis has been criticized because the sign and magnitude of the indices of behavioral reproductive isolation have been demonstrated to depend on the methods employed to measure them. I evaluated this criticism by applying the three common methods used in testing for behavioral reproductive isolation to the species Drosophila heteroneura and D. silvestris. the species used in the original development of the behavioral isolation hypothesis. The methods were female choice, male choice and multiple choice.

I found a similar direction of asymmetry for all three testing methods in the interspecific pairing, but not always in the intraspecific pairing between two populations of Drosophila silvestris that are believed to be in the process of speciation. Thus, it appears that the methods used to test the direction of behavioral reproductive isolation apply at the interspecific level, but are inconsistent at the intraspecific level.