Data from: Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually

For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1 year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult.

对于需要保护的物种而言，掌握其关键生活史特征与种群统计参数（如繁殖成体的数量与性比），是准确评估种群生存力的核心前提。具有温度依赖型性别决定（temperature-dependent sex determination）机制的物种，其初级性比极易出现严重偏倚；当前学界担忧，这类物种的成体性比或已存在类似偏倚，或因气候变暖进一步加剧偏倚。若缺乏相关生活史信息，便难以对这类影响进行预测与缓解。

对于海龟而言，由于难以在野外观测到雄性个体，雄性的繁殖间隔至今仍是未知参数。此前有研究提出，雄性繁殖周期可能短于雌性，这或许能缓解种群普遍偏雌性的性比失衡问题。

本研究阐明了如何借助基于分子技术的父权分析（paternity analysis）方法，首次实现了对多个繁殖季中海龟雄性个体繁殖间隔的评估。在针对绿海龟（Chelonia mydas）产卵场开展的本研究中，为期3年的观测期内，97%的雄性个体仅在单个繁殖季中被鉴定出拥有后代，这有力表明该产卵场的雄性海龟繁殖间隔通常长于1年。

研究结果同时显示，该种群的繁殖成体性比至少为1.3雄:1雌。本研究证实，针对难以直接观测或捕获的物种，通过重构亲本基因型开展基于分子技术的亲权推断（parentage inference），可作为监测其繁殖个体数量与性比的有效手段。