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Females of theDrosophila virilis group of species may vibrate their wings during courtship producing songs consisting of trains of successive sound pulses (pulse song) or sinusoidal hums (sine song). In the present study we describe these songs and study their role in courtship using a transition analysis. To find out which songs should be classified as pulse songs and which ones as sine songs, we studied the inheritance of different song types in interspecific F1 hybrids. In only a few species did the females produce large quantities of song in successful courtships. The males' reactions to female songs varied from licking and singing to stopping the courtship. Pulse trains with short and long intervals between successive pulses appeared to be different forms of the pulse song, while sine song (sinusoidal hums) was inherited independently of the pulse song.

In Drosophila montana, the male courtship song (especially the pulse characters of the song) plays an important role in sexual selection. The heritabilities and the amount of additive and residual variation in different characters of the male song were measured in two populations using father-son regression and sib analysis. The songs of the males from the Oulanka population were recorded for a second time after the males had been kept in 4°C for 6 months. Heritabilities measured for different song traits were non-significant in each case, largely due to high residual variation. During the cold treatment, the additive variation increased and the residual variation decreased in nearly all song traits. Our results suggest that genotype-environment interactions may increase the amount of additive variation between males in sexually selected song traits during overwintering, prior to the mating season of the flies.