Intraspecific variation in mating behaviour does not cause sexual isolation between Drosophila virilis strains

There is increasing evidence that mate recognition systems vary within species. We studied the courtship rituals of five Drosophila virilis strains to investigate this intraspecific variation. Males that actively and persistently courted the female without paying much attention to the female's behaviour were the most successful at copulating. Intraspecific variation in mating rituals was high, but not as high as at the species level and it was not high enough to cause sexual isolation between the strains. The differences in courtship interactions of the strains reflected their geographical origin. Males from one of the strains did not produce audible song during their courtship, but still mated with some females of all strains. The courtships of the 'mute' males proceeded in the same way as those of the normal males, and the male's wing vibration (even though silent and produced at a late stage) was still an important part of the courtship.