Courtship Behavior Analysis in Three Sibling Species of the Drosophila virilis Group

Abstract

Courtship behavior was studied in three sibling species of the Drosophila virilis group: D. virilis, D. lummei, and D. littoralis. The latter species was represented by two strains the founders of which had been collected in the habitats of the southern and northern races of D. littoralis whose status is equivalent to subspecies. Con- and heterospecific tests were analyzed by video-typing. Analyses of conspecific tests of D. virilis and D. lummei revealed no differences in the duration of courtship elements and their latencies. By contrast, comparison of heterospecific tests of ♀ D. virilis + ♂ D. lummei and ♀ D. lummei + ♂ D. virilis showed a much lower duration of all the main courtship elements (touching, licking, and singing), as well as a significantly lower percentage of copulation. Comparison of con- and heterospecific tests of the northern and southern races of D. littoralis revealed some differences in the courtship structure, but no obstacles to successful mating were observed in heterospecific tests of the two races. By contrast, large differences in the structure of the courtship ritual were observed in heterospecific reciprocal tests of D. littoralis + D. virilis and D. littoralis + D. lummei. The males of the D. virilis phylad lost interest in D. littoralis females immediately after the beginning of touching. On the contrary, D. littoralis males demonstrated a complete courtship ritual towards both D. lummei and D. virilis females. At the same time, all the heterospecific tests of D. lummei + D. littoralis and D. virilis + D. littoralis were characterized by the lowest incidence of copulation.