Courtship sounds and behaviour of the two saguaro-breeding Drosophila and their relatives

Abstract

The two saguaro-breeding Drosophila, D. nigrospiracula and D. mettleri, share striking morphological similarities even though they are not closely related. Drosophila mettleri is a member of the eremophila species complex, whereas D. nigrospiracula is a member of the anceps species complex. Both the courtship songs and courtship behaviour of the six species in these two complexes were examined. The objectives were (1) to investigate whether courtship behaviour follows the same evolutionary trend as the morphological traits and (2) to provide further insight about the evolution of courtship behaviour in these species. Results showed that the courtship song is a phylogenetically conservative trait within both species complexes. The pattern observed in the song parameters measured can be interpreted in terms of the degree with which hybrids can be formed in the laboratory and the extent to which sympatry occurs in the geographical distribution of the species within each species complex. Compared to many other species of Drosophila in the repleta group, those of the eremophila complex possess unique features, whereas those in the anceps complex have song characters that are commonly found throughout the species group.