High fidelity: extra-pair fertilisations in eight Charadrius plover species are not associated with parental relatedness or social mating system

Extra-pair paternity is a common reproductive strategy in many bird species. However, it remains unclear why extra-pair paternity occurs and why it varies among species and populations. Plovers (Charadrius spp.) exhibit considerable variation in reproductive behaviour and ecology, making them excellent models to investigate the evolution of social and genetic mating systems. We investigated inter- and intra-specific patterns of extra-pair parentage and evaluated three major hypotheses explaining extra-pair paternity using a comparative approach based on the microsatellite genotypes of 2,049 individuals from 510 plover families sampled from twelve populations that constituted eight species. Extra-pair paternity rates were very low (0 to 4.1% of chicks per population). No evidence was found in support of the sexual conflict or genetic compatibility hypotheses, and there was no seasonal pattern of extra-pair paternity (EPP). The low prevalence of EPP is consistent with a number of alternative hypotheses, including the parental investment hypothesis, which suggests that high contribution to care by males restricts female plovers from engaging in extra-pair copulations. Further studies are needed to critically test the importance of this hypothesis to plover mate choice.

婚外父权（extra-pair paternity, EPP）是众多鸟类中普遍存在的繁殖策略。然而，学界迄今尚未明确婚外父权的发生机制，以及其在不同物种与种群间的差异成因。鸻属（Charadrius spp.）鸟类的繁殖行为与生态特征存在显著变异，是探究社会与遗传交配系统演化的理想模型类群。本研究针对婚外父权的种间与种内模式展开分析，并基于覆盖8个物种、12个种群的510个鸻类家庭的2049个个体的微卫星基因型（microsatellite genotypes），通过比较研究方法对解释婚外父权的三大核心假说进行了验证。各种群的婚外父权发生率极低，仅为0至4.1%的雏鸟比例。本研究未发现支持性冲突假说（sexual conflict hypothesis）与遗传相容性假说（genetic compatibility hypothesis）的证据，且婚外父权未表现出季节动态特征。婚外父权的低发生率与诸多替代假说相符，其中包括亲本投入假说（parental investment hypothesis）：该假说认为雄性对育雏的高投入会限制雌性鸻类开展婚外交配的行为。未来仍需开展进一步研究，以严谨验证该假说对鸻类配偶选择的重要性。