INCOMPLETE BEHAVIORAL ISOLATION BETWEEN TWO DISTANTLY RELATED DROSOPHILA SPECIES

Two sympatric, distantly related Drosophila species, D. affinis and D. melanogaster, interact sexually in the laboratory and in the field. When mature males from one species are tested with females or sexually attractive males from the other species, the mature males perform courtship that, in most cases, is indistinguishable from the courtship that attractive conspecific flies elicit. Moreover, some of the D. affinis females that elicit courtship from D. melanogaster males copulate with them.