Are extra-pair males different from cuckolded males? A case study and a meta-analytic examination
Are extra-pair males different from cuckolded males? A case study and a meta-analytic examination
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DOI：
10.1111/mec.13124
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发表时间：
2015-04-01
影响因子：
4.9
通讯作者：
Nakagawa, Shinichi
中科院分区：
文献类型：
--
作者：
Hsu, Yu-Hsun;Schroeder, Julia;Nakagawa, Shinichi
传统的雌性额外配对模型假定雌性从额外配对行为中间接受益。在这些所谓的适应性模型下，额外配对的雄性被假设具有更相容的基因类型、更大的体型、夸张的装饰品或比戴绿帽子的雄性更老。或者，(非适应性的)模型认为雌性额外配对是一种副产品，假设雌性额外配对可以维持，即使这对雌性没有好处。例如，如果男性从额外配对中获得健康益处，而女性和男性额外配对行为是遗传相关的，这种情况就可能发生。如果额外配对的雄性能够提高它们说服或强迫雌性交配的能力，那么它们也会变得更老、更大。我们通过分析来自岛上的家雀种群的数据，调查了雌性的额外配对配偶是否在遗传和表型特征上与她的戴绿帽配偶有所不同。我们发现，额外配对的雄性比戴绿帽子的雄性年龄更大，这与两种模型都是一致的。然而，与来自适应模型的期望相反，额外配对和戴绿帽子的雄性具有相似的遗传关系，因此预期与雌性相容，并且具有相似的身体尺寸和第二性特征。我们还更新了之前的荟萃分析，考察了额外配对和戴绿帽子的雄性之间的差异。荟萃分析结果与我们家雀个案研究的结果相吻合。虽然我们不能完全排除对女性的间接好处，但非适应性模型可能更好地解释女性的额外配对。这些被忽视的替代模型值得更多的研究关注，这应该会提高我们对交配系统进化的理解。
Traditional models for female extra-pair matings assume that females benefit indirectly from extra-pair mating behaviour. Under these so-called adaptive models, extra-pair males are hypothesized to have more compatible genotypes, larger body size, exaggerated ornaments or to be older than cuckolded males. Alternatively, (nonadaptive') models that consider female extra-pair matings to be a by-product posit that female extra-pair mating can be maintained even if there is no benefit to females. This could happen if, for example, males gained fitness benefits from extra-pair mating, while female and male extra-pair mating behaviours were genetically correlated. Extra-pair males are also expected to be older and larger if this improves their ability to convince or coerce females to mate. We investigated whether a female's extra-pair mates differed from her cuckolded mate in both genetic and phenotypic traits by analysing data from an insular house sparrow population. We found that extra-pair males were older than cuckolded males, consistent with both models. However, in contrast to the expectations from from adaptive models, extra-pair and cuckolded males were of similar genetic relatedness, and hence expected compatibility, with the female, and had comparable body size and secondary sexual traits. We also updated previous meta-analyses examining differences between extra-pair and cuckolded males. The meta-analytic results matched results from our house sparrow case study. Although we cannot completely exclude indirect benefits for females, nonadaptive models may better explain female extra-pair matings. These neglected alternative models deserve more research attention, and this should improve our understanding of the evolution of mating systems.