Extra-pair paternity, age and paternal care: fitness consequences and genetic correlations

不忠在许多分类群中很常见，但我们仍然不知道选择压力如何塑造变异，并驱动额外配对行为的进化。雄性可以从额外配对的后代中获得额外的健康益处，因为额外配对的父亲不必花费资源进行昂贵的父母照顾。然而，雌性的情况并非如此，今天仍然不清楚为什么雌性会产生额外的后代。间接利益假说被认为可以解释女性的不忠行为，但并没有得到很好的支持。尽管有许多关于这个主题的研究，间接健身益处的经验证据充其量是模棱两可的。性对抗选择，即男性和女性的额外配对行为是遗传联系的，是另一种解释女性为什么会参与额外配对行为的假设，但这种证据很少。然而，如果不考虑伴侣之间的社会反馈效应，可能会掩盖潜在的遗传相关性。该项目旨在全面评估女性不忠的健康后果，重点是两个主要的成本来源，并评估两性之间的遗传相关性，以说明社会反馈。女性的一个主要成本来源可能是父亲照顾和一夫多妻制之间的负面联系。这种影响是比较好的建立在物种之间，但在个人内的变化，由此产生的健身后果和预测的选择压力，在很大程度上是未开发的。这可能是因为特别是成本很难评估，因为它们可能在个体内部和个体之间存在差异，这需要具体的分析，从而需要大的样本量。该项目所提供的关于野生鸟类的长期数据克服了这些问题，并允许进行详细的分析。第二个成本来源并不经常被承认，但可能有助于我们理解女性的不忠：被认为质量较高的老年男性通常比年轻男性拥有更多的额外配对后代。经验数据表明，年龄较大的男性父系后代的质量差，这可能会抵消直接健身好处老额外对父系理应获得。我建议进行详细的分析，在长期的数据，并补充这方面的重点实验圈养的个人，了解年龄相关的变化，额外的对行为。然后，我建议估计遗传相关性，并考虑社会反馈，间接影响，在额外的配对行为。最后，一个全面的适合度分析的成本和收益的额外对行为将综合的结果。该项目将使我们能够更好地区分间接遗传利益假说和拮抗选择假说，并进一步了解如何保持种群内额外配对行为的变化。

Infidelity is common among many taxa, but we still do not know how selection pressures shape variation in, and drive evolution of extra-pair behavior. Males can reap additional fitness benefits from extra-pair offspring, because extra-pair fathers do not have to spend resources on costly parental care. This is however not the case for females, and today it is still unclear why females produce extra-pair offspring. The indirect benefits hypothesis has been suggested to explain female infidelity, but it is not well supported. Despite many studies on the topic, empirical evidence for indirect fitness benefits is ambiguous at best. Sexually antagonistic selection, where male and female extra-pair behavior are genetically linked, is another hypothesis to explain why females engage in extra-pair behavior, but empirical for this evidence is rare. Not accounting for social feedback effects between meting partners however may cloak potential genetic correlations. This project aims at a comprehensive assessment of the fitness consequences of female infidelity, focusing on two major sources of costs, and at assessing the genetic correlation between the sexes accounting for social feedback. One major source of costs to females may be the negative association between paternal care and polygamy. This effect is relatively well established among species, but the variation within-individuals, the resulting fitness consequences and predicted selection pressures, are largely unexplored. This may be because especially the costs are hard to assess, as they likely differ within- and between individuals, which needs specific analyses, in turn requiring large sample sizes. The uniquely suited long-term data on wild birds available for this project overcome these problems, and allow detailed analyses. A second source of costs is not often acknowledged, but may contribute greatly to our understanding of female infidelity: Older males of supposedly higher quality often have more extra-pair offspring than younger males. Empirical data suggests that older males sire offspring of poor quality, which could offset the direct fitness benefits old extra-pair sires supposedly gain. I propose to conduct detailed analyses in the long-term data and to complement this by focused experiments on captive individuals, to understand age-related variation in extra-pair behaviour. I then propose to estimate the genetic correlation, and to account for social feedback, the indirect effects, in extra-pair behavior. Finally, a comprehensive fitness analysis of costs and benefits of extra-pair behavior will synthesize the results. This project will allow us to better distinguish between the indirect genetic benefits hypothesis and the antagonistic selection hypothesis, and further our understanding of how variation in extra-pair behaviors within populations can be maintained.