Social effects on fruit fly courtship song

Courtship behaviour in Drosophila has often been described as a classic innate behavioural repertoire, but more recently extensive plasticity has been described. In particular, prior exposure to acoustic signals of con- or heterspecific males can change courtship traits in both sexes that are liable to be important in reproductive isolation. However, it is unknown whether male courtship song itself is socially plastic. We examined courtship song plasticity of two species in the Drosophila melanogaster subgroup. Sexual isolation between the species is influenced by two male song traits, the inter-pulse interval (IPI) and sine song frequency (SSF). Neither of these showed plasticity when males had prior experience of con- and heterospecific social partners. However, males of both species produced longer bursts of song during courtship when they were exposed to social partners (either con- or heterospecific) than when they were reared in isolation. D. melanogaster carrying mutations affect...