COURTSHIP SOUND PRODUCTION IN TWO SYMPATRIC SIBLING DROSOPHILA SPECIES.

Courting males of Drosophila persimilis produce a pulsed "vibration sound," with frequency of oscillation and pulse repetition rate markedly different from that of D. pseudoobscura. These differences probably contribute to reproductive isolation. Flight frequency is the same in both species. Brief "preliminary sounds" are common and the same in both species. Males with large parts of both wings removed produce nearly normal vibration sounds, and normal preliminary sounds.