Behavioural pleiotropy of the yellow gene in Drosophila melanogaster

Abstract

The yellow mutant (y − 1:0·0) of Drosophila melanogaster shows a reduction in body pigmentation associated with a decrement in locomotor activity and in male competitive mating ability. The effects of the mutant gene are specific to locomotor activity in the adult fly, measures of larval activity being unaffected. In the presence of active females yellow males offer a reduced intensity of sexual stimulation because they are less able to maintain contact during courtship. However, the impaired locomotor performance of yellow males is not the general cause for their reduced competitive mating ability, since the stimuli provided by yellow mutants courting inactive females appear to be both quantitatively and qualitatively indistinguishable from those of their wild-type male sibs. Nor is there any good evidence, as measured by the frequency of rejection responses, that the courtship stimulation offered by the yellow males is less acceptable to the females. The mutant males are nevertheless unsuccessful in achieving copulation with such females. It is suggested that impairment of mating ability in yellow males may be caused by changes in the efficiency for mating of their secondary sexual structures due to the effect of the yellow gene on the properties of the cuticle. © 1976, Cambridge University Press. All rights reserved.