COURTSHIP SOUNDS AND BEHAVIOR OF THE 2 SAGUARO-BREEDING DROSOPHILA AND THEIR RELATIVES

The two saguaro-breeding Drosophila, D. nigrospiracula and D. mettleri , share striking morphological similarities even though they are not c losely related. Drosophila mettleri is a member of the eremophila spec ies complex, whereas D. nigrospiracula is a member of the anceps speci es complex. Both the courtship songs and courtship behaviour of the si x species in these two complexes were examined. The objectives were (1 ) to investigate whether courtship behaviour follows the same evolutio nary trend as the morphological traits and (2) to provide further insi ght about the evolution of courtship behaviour in these species. Resul ts showed that the courtship song is a phylogenetically conservative t rait within both species complexes. The pattern observed in the song p arameters measured can be interpreted in terms of the degree with whic h hybrids can be formed in the laboratory and the extent to which symp atry occurs in the geographical distribution of the species within eac h species complex. Compared to many other species of Drosophila in the repleta group, those of the eremophila complex possess unique feature s, whereas those in the anceps complex have song characters that are c ommonly found throughout the species group. (C) 1995 The Association f or the Study of Animal Behaviour