No genetic correlation between the sexes in mating frequency in the bean beetle, Callosobruchus chinensis.

Female multiple mating, which is common in animals, may have evolved not in response to fitness advantages to females but as a genetic corollary to selection on males to mate frequently. This nonadaptive hypothesis assumes a genetic correlation between females and males in mating frequency, which has received a few empirical investigations. We tested this hypothesis by observing the correlated response in male mating frequency in the adzuki bean beetle, Callosobruchus chinensis to artificial selection on female propensity to remate. Compared to control females, females from lines selected for increased or decreased female propensity to remate had, respectively, higher or lower mating frequency measured by the number of mating within a given period. This indicates that female receptivity to remating is genetically correlated with female mating frequency, and thus the artificial selection for female propensity to remate influenced female mating frequency. In contrast, males from the selected lines that diverged in female mating frequency did not vary significantly in their mating frequency. These results indicate that there is no genetic correlation between the sexes in mating frequency in C. chinensis. This study shows that the reason why females in C. chinensis remate despite suffering fitness costs cannot be explained by indirect selection resulting from selection on males to mate multiple times.