Phenological traits, such as the timing of reproduction, are often influenced by social interactions between paired individuals. Such partner effects may occur when pair members affect each other’s prebreeding environment. Partner effects can be environmentally and/or genetically determined, and quantifying direct and indirect genetic effects is important for understanding the evolutionary dynamics of phenological traits. Here, using 26 years of data from a pedigreed population of a migratory seabird, the common tern (Sterna hirundo), we investigate male and female effects on female laying date. We find that female laying date harbors both genetic and environmental variation and is additionally influenced by the environmental and, to a lesser extent, genetic component of its mate. We demonstrate this partner effect to be largely explained by male arrival date. Interestingly, analyses of mating patterns with respect to arrival date show mating to be strongly assortative, and using simulations we show that assortative mating leads to overestimation of partner effects. Our study provides evidence for partner effects on breeding phenology in a long-distance migrant while uncovering the potential causal pathways underlying the observed effects and raising awareness for confounding effects resulting from assortative mating or other common environmental effects.

中文翻译：

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了解繁殖物候的社会动态：远距离移民的间接遗传效应和交配。

物候特性（例如繁殖时间）通常受配对个体之间的社会互动影响。当配对成员影响彼此的预育环境时，可能会发生这种伴侣效应。伴侣效应可以在环境和/或遗传上确定，量化直接和间接遗传效应对于理解物候性状的进化动态很重要。在这里，用26年数据从迁徙海鸟的纯种人群中，普通燕鸥（燕鸥），我们调查了男性和女性对女性产卵日期的影响。我们发现雌性产卵既具有遗传变异又具有环境变异，并且还受其配偶的环境以及较小程度的遗传成分影响。我们证明这种伴侣效应在很大程度上取决于男性的到来日期。有趣的是，关于到达日期的交配模式的分析表明，交配具有很强的分类性，并且使用模拟我们发现，分类交配会导致对伴侣效应的高估。我们的研究提供了证据，说明了长途移民中配偶对育种物候的影响，同时揭示了所观察到的影响的潜在因果途径，并提高了人们对因杂种交配或其他常见环境影响而产生的混杂影响的认识。