Copulatory song in three species of the Drosophila montium subgroup extends copulation and shows unusual genetic control

Most Drosophila species produce species-specific male courtship song as part of their precopulatory courtship repertoire. Females usually mate most quickly when stimulated with appropriate song. Unusually, males of Drosophila lini and its sibling species sing sine song only during copulation. Sine song frequency is high in D. lini and Drosophila ogumai and lower in Drosophila ohnishii. Drosophila ogumai and D. lini are allopatric, although the range of D. ohnishii may meet or overlap with that of D. ogumai or D. lini. We conducted playback experiments with each species to examine the role of sine song frequency. Copulation duration increased for females of D. lini or D. ogumai when stimulated with high-frequency (240–250 Hz) artificial song and for females of D. ohnishii when stimulated with low-frequency (170–180 Hz) artificial song. This suggests that sine song frequency extends copulation duration in the three species and that species-typical song is more effective. We also examined song frequency in crosses between D. lini and D. ohnishii to assess its genetic control. Analysis of F1 and backcross generations between D. lini and D. ohnishii showed that sine song frequency is mainly due to additive autosomal variation, although a transgressive effect of the X chromosome and maternal or Y-linked effects were also found.