Faithful females receive more help: the extent of male parental care during incubation in relation to extra-pair paternity in songbirds

Parental care provided by males occurs in a diverse array of animals and there are large differences among species in its extent compared to female care. However, social and ecological factors responsible for interspecific differences in male’s share of parental duties remain unclear. Genetic fidelity of females has been long considered important. Theory predicts that females should receive more help from their mates in raising the offspring in species with high genetic fidelity. Using avian incubation behavior as a model system, we confirmed this prediction. The extent of male’s help during incubation increased with decreasing rate of extra-pair paternity across species (22 species of socially monogamous songbirds from 13 families; male’s share of incubation ranged from 6% to 58%), even after accounting for covariates, biases in species selection and intraspecific variability. Moreover, this result was not sensitive to two different phylogenies and branch length estimates. We suggest t...雄性双亲抚育（parental care）行为广泛分布于各类动物类群，且相较于雌性抚育，不同物种间雄性抚育的投入程度差异显著。然而，造成物种间雄性双亲抚育职责占比出现种间差异的社会与生态因子，目前仍未明确。长期以来，雌性的遗传忠贞度被认为是关键影响因素之一。相关理论预测，在雌性遗传忠贞度较高的物种中，雌性可从配偶处获得更多抚育后代的帮助。本研究以鸟类孵卵行为为模型系统，对13个科的22种社会单配型鸣禽展开分析，结果显示：跨物种层面上，雄性在孵卵期的抚育程度随额外配对父权（extra-pair paternity）发生率的降低而升高（雄性孵卵占比区间为6%至58%）；即便在控制协变量、物种选择偏差与种内变异后，该结果依然稳健。此外，这一结论不受两种不同系统发育树（phylogenies）及分支长度估计方式的影响。我们提出……