The evolution of female multiple mating as a life-history strategy

尽管大多数解释雌性多次交配（一妻多夫制）进化的理论都是基于性选择，但它们可能与生活史策略有关。在日本，中国胼胝体作为模型系统在实验室饲养了70多年。该实验室菌株的雌性是单雄型的，而最近从野外发现的菌株的雌性是多雄型的。在标准饲养制度下，新出现的成虫不提供食物，只提供豆类作为产卵地点。在这种情况下，雌性在饿死之前必须产卵。因此，一夫一妻制可能是由于对早期繁殖基因型的无意选择造成的。为了验证这一假设，我在繁殖时进行了基于喂养方式的人工选择实验（不喂养的早期和喂养的晚期）。在20轮以上的选择后，雌性交配频率在未饲喂的早期繁殖系中逐渐下降，而在其他系中保持较高的交配频率。

Although most theories explaining the evolution of female multiple mating (polyandry) are based on sexual selection, they can be relevant to life-history strategies. In Japan, Callosobruchus chinensis has been reared in the laboratory for over 70 years as a model system. Females in this lab strain are monandrous while females from recently established strains from the wild are polyandrous. In the standard rearing regime newly emerged adults have been supplied with no food but beans as oviposition site. Under such conditions females have to lay eggs before they starve to death. Therefore, monandry may have resulted from inadvertent selection for early reproducing genotypes. To test this hypothesis I conducted artificial selection experiments based on feeding regime-age at reproduction (unfed-early versus fed-late). After more than 20 selection bouts, female mating frequency decreased gradually in the unfed-early reproducing lines, whereas it remained high in the other lines.