Data from: Offspring fitness varies with parental extra-pair status in song sparrows, Melospiza melodia

Numerous studies have tested for indirect selection on female extra-pair reproduction (EPR) by quantifying whether extra-pair young (EPY) are fitter than their within-pair young (WPY) maternal half-siblings. In contrast, the hypothesis that offspring of EPY and WPY (rather than the EPY and WPY themselves) differ in fitness has not been tested, even though inter-generational effects of parental extra-pair status on offspring fitness could alter the magnitude and direction of indirect selection on EPR. We tested whether offspring of EPY song sparrows, Melospiza melodia, were more likely to recruit or produce hatched or recruited offspring over their lifetimes than offspring of WPY. Hatchlings with one or two EPY parents were more likely to recruit and produce hatched offspring than hatchlings with two WPY parents. Furthermore, these relationships differed between maternal versus paternal extra-pair status. Hatchlings with EPY fathers were more likely to recruit and produce offspring than hatchlings with WPY fathers. In contrast, hatchlings with EPY mothers were as likely to recruit as hatchlings with WPY mothers and tended to be less likely to produce recruited offspring. Depending on the causal genetic and environmental mechanisms, such conflicting inter-generational relationships between parental extra-pair status and offspring fitness could substantially influence the evolutionary dynamics of EPR.已有大量研究通过量化比较婚外配子代（extra-pair young, EPY）与其母本半同胞的婚内配子代（within-pair young, WPY）的适合度差异，检验针对雌性婚外配繁殖（female extra-pair reproduction, EPR）的间接选择作用。与之相对，"婚外配子代与婚内配子代的后代（而非子代自身）存在适合度差异"这一假说尚未得到检验——尽管亲本婚外配状态对子代适合度的跨代效应，可能会改变针对EPR的间接选择的强度与方向。本研究以歌带鹀（Melospiza melodia）为研究对象，检验婚外配子代的后代相较于婚内配子代的后代，是否在其一生中更易成功招募入种群，或产出可孵化的子代、成功招募入种群的子代。拥有1个或2个EPY亲本的孵化幼鸟，相较于拥有2个WPY亲本的孵化幼鸟，更易被招募入种群并产出可孵化的子代。此外，上述关联因母本与父本的婚外配状态不同而存在差异：父本为EPY的孵化幼鸟，其种群招募成功率与子代产出率均高于父本为WPY的个体；与之相对，母本为EPY的孵化幼鸟，其种群招募成功率与母本为WPY的个体无显著差异，但产出可成功招募入种群的子代的概率往往更低。根据其潜在的遗传与环境作用机制，亲本婚外配状态与子代适合度之间的这类矛盾跨代关联，可能会显著影响EPR的进化动态。