School of Zoology, University of Tasmania, PO Box 05, Hobart, Tas. 7001, Australia Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, UK.
Mol Ecol. 2011 Feb;20(4):844-52. doi: 10.1111/j.1365-294X.2010.04976.x. Epub 2010 Dec 28.
Social monogamy has traditionally been suggested to be maintained because of weak sexual selection on male partner acquisition. However, the ubiquitous incidence of extra-pair paternity suggests that sexual selection can be strong in monogamous systems, although studies partitioning variance in male reproductive success have come to mixed conclusions. Here, we use detailed field data to examine variance in male reproductive success and its implications for the maintenance of sociality in a population of the socially monogamous lizard Egernia whitii. We show that both within-pair and, to a lesser extent, extra-pair partner acquisition contribute to the variance in male reproductive success, resulting in considerable opportunity for sexual selection. Despite this, levels of multiple mating are lower in Egernia compared to other reptiles, suggesting that male partner acquisition is constrained. We suggest that this constraint may be a result of strong territoriality combined with sexual conflict over multiple mating generated by costs of extra-pair paternity to females as a result of facultative male care. This has the potential to limit sexual selection by reducing variance in male reproductive success and therefore contribute to the maintenance of complex social organization.
社会一夫一妻制传统上被认为是由于对男性伴侣获得的弱性选择而得以维持。然而，广泛存在的婚外配表明，性选择在一夫一妻制系统中可能很强，尽管将雄性生殖成功的方差进行划分的研究得出了不同的结论。在这里，我们使用详细的实地数据来研究雄性生殖成功的方差及其对社会一夫一妻制蜥蜴 Egernia whitii 种群社会性维持的影响。我们表明，在配对内和在较小程度上，婚外伴侣的获得都有助于雄性生殖成功的方差，从而为性选择提供了很大的机会。尽管如此，与其他爬行动物相比，Egernia 的多次交配水平较低，这表明雄性伴侣的获得受到限制。我们认为，这种限制可能是由于强烈的领地性和对多配偶的性冲突共同导致的，这种性冲突是由于雄性对雌性的强制性照顾而导致的婚外配产生的成本。这有可能通过减少雄性生殖成功的方差来限制性选择，从而有助于维持复杂的社会组织。
