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 t...

在社会一夫一妻制物种中，雌性不忠行为的一项被预测的代价是：配偶遭背叛的雄性会减少亲代抚育（parental care）的投入。该关联在跨物种层面具有稳健性，但在物种内部的相关证据却模棱两可。我们尚不清楚：个体雄性在与不忠雌性配对时，是否会相较于与忠贞雌性配对时降低抚育投入（即雄性个体内调整效应）；抑或是，与不忠雌性配对的雄性本身就是那些总体上提供更少亲代抚育的雄性（即雄性个体间效应）。我们针对一种野生雀形目鸟类（passerine）收集了极为详尽的长期重复观测数据集，借此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，相较于巢穴内的配偶不忠情况，雄性会调整自身的育雏供食（paternal provisioning）行为，但不会调整孵卵投入（incubation effort）。这一效应主要由雌性始终如一的忠贞程度差异所驱动。尚无证据表明……