Data from: Adult sex ratio and operational sex ratio exhibit different temporal dynamics in the wild

Adult sex ratio (ASR, the proportion of adult males in the adult population) and operational sex ratio (OSR, the proportion of sexually active males in the mating pool) are fundamental properties of breeding populations and they are often linked to mating systems and sexual selection. However, ASR and OSR emerge via different routes in a population and may exhibit different temporal patterns. Here we use data from a well-monitored polygamous snowy plover Charadrius nivosus population sampled over three consecutive breeding seasons, to investigate whether temporal changes in ASR relate to changes in OSR. We found that snowy plovers exhibited male-biased ASR and OSR. Consistent with theoretical expectations, OSR was more variable than ASR. However, there was no consistent relationship between OSR and ASR: in only one out of three study years we found a weak positive relationship (r = 0.22). The lack of association was corroborated by time-series analyses and sensitivity tests. Our work therefore suggests that ASR and OSR exhibit different temporal patterns in a polygamous population, and we call for further theoretical and empirical studies that analyse their relationship across a range of different breeding systems.

成体性比（Adult sex ratio, ASR，即成体种群中成体雄性的占比）与操作性别比（operational sex ratio, OSR，即交配库中性活跃雄性的占比）是繁殖种群的核心属性，二者常与交配系统及性选择密切相关。然而，成体性比与操作性别比在种群中通过不同路径产生，可能呈现迥异的时间动态模式。本研究基于连续三个繁殖季对一夫多妻制雪鸻（Charadrius nivosus）种群的严格监测数据，探究成体性比的时间变化是否与操作性别比的变化存在关联。研究结果表明，雪鸻种群的成体性比与操作性别比均表现为雄性偏倚。与理论预期相符，操作性别比的波动幅度显著大于成体性比。但二者并未呈现稳定的关联：仅在三个研究年份中的一年，二者存在微弱的正相关关系（r = 0.22）。时间序列分析与敏感性检验进一步佐证了这一无关联的结论。综上，本研究显示在一夫多妻制种群中，成体性比与操作性别比呈现不同的时间动态模式，同时呼吁学界开展更多覆盖不同繁殖系统的理论与实证研究，以解析二者的关联机制。