Data from: Fine-scale genetic structure and helping decisions in a cooperatively breeding bird

In animal societies, characteristic demographic and dispersal patterns may lead to genetic structuring of populations, generating the potential for kin selection to operate. However, even in genetically structured populations, social interactions may still require kin discrimination for cooperative behaviour to be directed towards relatives. Here, we use molecular genetics and long-term field data to investigate genetic structure in an adult population of long-tailed tits Aegithalos caudatus, a cooperative breeder in which helping occurs within extended kin networks, and relate this to patterns of helping with respect to kinship. Spatial autocorrelation analyses reveal fine-scale genetic structure within our population, such that related adults of either sex are spatially clustered following natal dispersal, with relatedness among nearby males higher than that among nearby females, as predicted by observations of male-biased philopatry. This kin structure creates opportunities for failed breeders to gain indirect fitness benefits via redirected helping, but crucially, most close neighbours of failed breeders are unrelated and help is directed towards relatives more often than expected by indiscriminate helping. These findings are consistent with the effective kin discrimination mechanism known to exist in long-tailed tits, and support models identifying kin selection as the driver of cooperation.在动物社会中，典型的种群统计与扩散模式可导致种群形成遗传结构，从而为亲缘选择（kin selection）的运作提供可能。然而，即便在具有遗传结构的种群中，社会互动仍需借助亲缘识别（kin discrimination），才能将合作行为定向指向亲属。本研究利用分子遗传学与长期野外数据，对银喉长尾山雀（Aegithalos caudatus）的成体种群遗传结构展开调查——该物种为合作繁殖鸟类，其互助行为发生于扩展的亲缘网络中——并将该遗传结构与基于亲缘关系的互助模式相关联。空间自相关分析显示，本研究种群存在精细尺度的遗传结构：两性相关成体在出生扩散后呈现空间聚集状态，且邻近雄性间的亲缘关系高于邻近雌性间的亲缘关系，这与雄性偏置恋巢性的观测结果一致。这种亲缘结构为繁殖失败的个体提供了通过转向互助获得间接适合度收益的机会，但关键在于，繁殖失败个体的绝大多数近邻均无亲缘关系，且其互助行为指向亲属的频率远高于随机互助的预期概率。本研究结果与已知存在于银喉长尾山雀中的高效亲缘识别机制相符，并支持以亲缘选择作为合作行为驱动力的相关模型。