Møller A P, Birkhead T R
Zoological Institute, Copenhagen University, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark.
Department of Animal and Plant Sciences, The University, P. O. Box 601, Sheffield, S10 2UQ, United Kingdom.
Evolution. 1994 Aug;48(4):1089-1100. doi: 10.1111/j.1558-5646.1994.tb05296.x.
A positive association between plumage brightness of male birds and the degree of polygyny may be the result of sexual selection. Although most birds have a socially monogamous mating system, recent paternity analyses show that many offspring are fathered by nonmates. Extrapair paternity arises from extrapair copulations which are frequently initiated by females. Not all females will be able to mate with a male of the preferred phenotype, because of the mating decisions of earlier paired females; extrapair copulations may be a means for females to adjust their precopulation mate choice. We use two comparative analyses (standardized linear contrasts and pairwise comparisons between closely related taxa) to test the idea that male plumage brightness is related to extrapair paternity. Brightness of male plumage and sexual dimorphism in brightness were positively associated with high levels of extrapair paternity, even when potentially confounding variables were controlled statistically. This association between male brightness and extrapair paternity was considerably stronger than the association between male brightness and the degree of polygyny. Cuckoldry thus forms an important component of sexual selection in birds.
雄鸟羽毛亮度与多配偶程度之间的正相关可能是性选择的结果。尽管大多数鸟类具有社会一夫一妻制的交配系统，但最近的亲权分析表明，许多后代的父亲并非配偶。婚外父权源于雌性频繁发起的婚外交配。由于较早配对的雌性的交配决定，并非所有雌性都能与具有首选表型的雄性交配；婚外交配可能是雌性调整其交配前配偶选择的一种方式。我们使用两种比较分析（标准化线性对比和近缘类群之间的成对比较）来检验雄鸟羽毛亮度与婚外父权相关的观点。即使在对潜在的混杂变量进行统计控制的情况下，雄鸟羽毛的亮度和亮度上的两性异形与高水平的婚外父权呈正相关。雄鸟亮度与婚外父权之间的这种关联比雄鸟亮度与多配偶程度之间的关联要强得多。因此，戴绿帽现象构成了鸟类性选择的一个重要组成部分。
