Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany.
Department of Collective Behaviour, Max Planck Institute of Animal Behavior, Konstanz, Germany.
Proc Biol Sci. 2020 Feb 26;287(1921):20192606. doi: 10.1098/rspb.2019.2606. Epub 2020 Feb 19.
Despite decades of research, our understanding of the underlying causes of within-population variation in patterns of extra-pair paternity (EPP) remains limited. Previous studies have shown that extra-pair mating decisions are linked to both individual traits and ecological factors. Here, we examine whether social associations among individuals prior to breeding also shape mating patterns, specifically the occurrence of EPP, in a small songbird, the blue tit. We test whether associations during the non-breeding period predict (1) future social pairs, (2) breeding proximity (i.e. the distance between breeding individuals) and (3) the likelihood that individuals have extra-pair young together. Individuals that were more strongly associated (those that foraged more often together) during winter tended to nest closer together. This, by itself, predicts EPP patterns, because most extra-pair sires are close neighbours. However, even after controlling for spatial effects, female-male dyads with stronger social associations prior to breeding were more likely to have extra-pair young. Our findings reveal a carry-over from social associations into future mating decisions. Quantifying the long-term social environment of individuals and studying its dynamics is a promising approach to enhance our understanding of the process of (extra-)pair formation.
尽管经过了几十年的研究，我们对于群体内个体间发生婚外交配（EPP）的模式的潜在原因的理解仍然有限。先前的研究表明，婚外交配的决定与个体特征和生态因素都有关。在这里，我们检验了在繁殖之前个体之间的社会联系是否也会影响交配模式，特别是在一种小型鸣禽——蓝山雀中，EPP 的发生。我们测试了在非繁殖期的联系是否可以预测（1）未来的社会对，（2）繁殖接近度（即繁殖个体之间的距离）和（3）个体是否有共同的婚外后代的可能性。在冬季，联系更紧密的个体（那些一起觅食更频繁的个体）往往会更靠近地筑巢。这本身就可以预测 EPP 模式，因为大多数婚外的亲代都是近邻。然而，即使在控制了空间效应之后，在繁殖前具有更强社会联系的雌雄对更有可能拥有婚外后代。我们的发现揭示了从社会联系到未来交配决策的延续。量化个体的长期社会环境并研究其动态是增强我们对（额外）配对形成过程的理解的一种很有前途的方法。
