EFFECTS OF COURTSHIP SONG IN INTERSPECIFIC CROSSES AMONG THE SPECIES OF THE DROSOPHILA-AURARIA COMPLEX (DIPTERA, DROSOPHILIDAE)

The courtship behavior and the effects of courtship song in inter- and intraspecific crosses were studied in the four sympatric species of t he Drosophila auraria complex: D. auraria, D. biauraria, D. subauraria , and D, triauraria. Orientation, tapping, and vibration (the repertoi res of male courtship) were observed in both inter- and intraspecific crosses, suggesting that signals from heterospecific females were enou gh to elicit such male behaviors. The crossability tests with wingless or winged heterospecific males (tests for wing effects) revealed that winged heterospecific males copulated less than wingless ones in all four species but not all the pairwise cases. Since the crossability te sts with aristaless females (deaf) or normal females showed essentiall y the same results as the tests for wing effects, we concluded that th e sound produced by wing vibration plays an important role and that th e wing movement itself is less important. These findings suggest that courtship songs are of great importance in mate discrimination and the sexual isolation between the species of this complex.