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Abstract：
Hamilton\'s local mate competition theory provided an explanation for extraordinary female-biased sex ratios in a range of organisms. When mating takes place locally, in structured populations, a female-biased sex ratio is favored to reduce competition between related males, and to provide more mates for males. However, there are a number of wasp species in which the sex ratios appear to more female biased than predicted by Hamilton\'s theory. It has been hypothesized that the additional female bias in these wasp species results from cooperative interactions between females. We investigated theoretically the extent to which cooperation between related females can interact with local mate competition to favor even more female-biased sex ratios. We found that (i) cooperation between females can lead to sex ratios that are more female biased than predicted by local competition theory alone, and (ii) sex ratios can be more female biased when the cooperation occurs from offspring to mothers before dispersal, rather than cooperation between siblings after dispersal. Our models formally confirm the verbal predictions made in previous experimental studies, which could be applied to a range of organisms. Specifically, cooperation can help explain sex ratio biases in Sclerodermus and Melittobia wasps, although quantitative comparisons between predictions and data suggest that some additional factors may be operating.
摘要：
汉密尔顿的局部伴侣竞争理论为一系列生物中非凡的女性偏见性别比例提供了解释。当交配发生在当地时，在结构化人群中，偏向女性的性别比例有利于减少相关男性之间的竞争，并为男性提供更多伴侣。然而,有许多黄蜂物种的性别比例似乎比汉密尔顿理论预测的更有女性偏见。据推测，这些黄蜂物种中的其他雌性偏见是由雌性之间的合作相互作用引起的。我们从理论上调查了相关女性之间的合作可以与当地伴侣竞争互动的程度，以支持更多女性偏见的性别比例。我们发现（i）女性之间的合作会导致性别比例比单独由本地竞争理论预测的更有女性偏见，和(Ii)性别比例可能更有女性偏见时，合作发生在后代和母亲之前，而不是分散后兄弟姐妹之间的合作。我们的模型正式证实了先前实验研究中的口头预测，可以应用于一系列生物。具体来说,合作可以帮助解释硬皮和蜂蜂的性别比例偏差，尽管预测和数据之间的定量比较表明，一些额外的因素可能正在起作用。
