Data from: Predictably philandering females prompt poor paternal provisioning

One predicted cost of female infidelity in socially monogamous species is that cuckolded males should provide less parental care. This relationship is robust across species, but evidence is ambiguous within species. We do not know whether individual males reduce their care when paired with cheating females compared with when paired with faithful females (within-male adjustment) or, alternatively, if the males that pair with cheating females are the same males that provide less parental care in general (between-male effect). Our exceptionally extensive long-term data set of repeated observations of a wild passerine allows us to disentangle paternal care adjustment within males-within pairs and between males-while accounting for environmental variables. We found a within-male adjustment of paternal provisioning, but not incubation effort, relative to the cuckoldry in their nest. This effect was mainly driven by females differing consistently in their fidelity. There was no evidence that this within-male adjustment also took place across broods with the same female, and we found no between-male effect. Interestingly, males that gained more extrapair paternity provided less care. Data from a cross-foster experiment suggested that males did not use kin recognition to assess paternity. Our results provide insight into the role of individual variation in parental care and mating systems.

在社会单配制物种（socially monogamous species）中，雌性不忠的一项预测性代价是，被戴绿帽的雄性（cuckolded males）会减少亲代抚育（parental care）投入。该种间关联在多个物种类群中均得到稳健验证，但种内相关证据却模棱两可。目前我们仍不清楚，相较于与忠贞雌性交配的雄性，与不忠雌性交配的雄性是否会降低自身抚育投入（即雄性个体内的调整效应）；抑或是，与不忠雌性交配的雄性本身就是那些一贯更少提供亲代抚育的雄性（即雄性个体间的效应）。我们针对一种野生雀形目鸟类（passerine）开展的大规模长期重复观测数据集，使我们得以在控制环境变量的前提下，区分雄性个体内、配对间以及个体间的亲代抚育调整模式。研究发现，雄性会根据其巢中发生的配偶不忠情况，调整自身的育雏投喂行为，但不会改变孵卵投入。这一效应主要源于雌性在忠贞度上存在稳定的个体差异。未发现该雄性个体内的调整效应会在与同一雌性交配的多窝雏鸟中出现，同时也未观测到雄性个体间的效应。有趣的是，获得更多配对外父权（extrapair paternity）的雄性，其亲代抚育投入更少。交叉抚育实验（cross-foster experiment）的数据表明，雄性并未通过亲属识别（kin recognition）来评估父权归属。本研究结果为理解亲代抚育与交配系统中的个体变异的作用提供了新的认知视角。