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

尽管大多数解释女性多配偶(一夫多妻制)进化的理论都是建立在性选择的基础上的，但它们可能与生活史策略有关。在日本，Callsobruchus chinensis作为模式系统在实验室饲养已有70多年的历史。在这个实验室品系中的雌性是单性的，而来自最近建立的野生品系的雌性是多雄的。在标准饲养模式下，新羽化的成虫只得到豆类作为产卵场所，而不提供食物。在这种情况下，雌性在饿死之前必须产卵。因此，一夫多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，我进行了人工选择实验，基于繁殖时的饲养制度-年龄(早期未喂养与后期饲养)。经过20多轮的选择后，未取食的早熟繁殖系的雌性交配频率逐渐下降，而其他品系的雌性交配频率仍然很高。

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.