Heritable variation in polyandry in Callosobruchus chinensis

The evolution of polyandry remains controversial. Various hypotheses that account for its evolution assume heritable variation in polyandry. We compared the frequency of female remating in 10 strains of the adzuki bean beetle, Callosobruchus chinensis, then made crosses between populations of high and low remating frequencies to investigate the mode of inheritance of polyandry. We found significant heritable variation in polyandry between the strains. Lower levels of polyandry were found in populations derived from long-term laboratory cultures than in those from recently established ones, suggesting that a selection pressure favoured monandry in the laboratory cultures. F1 offspring from reciprocal crosses between strains with high and low frequencies of female remating had frequencies similar to that of the strain with a high remating frequency, suggesting that polyandry is inherited with dominance in C. chinensis, unlike any other species reported to date. This study indicates that polyandry can evolve in response to selection in C. chinensis.