The relationship between locomotor activity and sexual behaviour in ebony strains of Drosophila melanogaster

Male flies homozygous for the ebony¹¹ mutant allele suffer a severe visual impairment and consequently show poor mating success. However, ebony males show improved mating in darkness because they initiate courtship more quickly than in the light. They also exhibit a competitive superiority over wild-type males under darkened conditoons that correlates with the observed increase in the mutant's locomotor activity. Locomotor activity levels were subsequently shown to correlate with several indices of mating success under both dark and illuminated conditions. The evolutionary implications of this relationship between the two characters are discussed.