Bidirectional selection for female propensity to remate in the bean beetle, Callosobruchus chinensis

The evolution of female multiple mating, or polyandry, is difficult to comprehend and thus has been the subject of a large number of studies. However, there is only a little evidence for genetic variation in polyandry, although the evolution of a trait via selection requires genetic variation that enables the trait to respond to selection. We carried out artificial selection for increased and decreased female propensity to remate as a measure of polyandry to investigate whether this trait has a genetic component that can respond to selection in the adzuki bean beetle, Callosobruchus chinensis. Artificial selection produced responses in both directions and divergence between the selection lines in the female propensity to remate. Although the experimental design adopted in this study selected jointly for female receptivity to remating, which is a trait of females, and male ability to inhibit female remating-both of which are associated with female propensity to remate-the observed response to selection was attributable only to the female receptivity to remating. This study indicates that the female receptivity to remating has significant additive genetic variation and can evolve according to whether remating is advantageous or disadvantageous to females in C. chinensis.