Breeding sex ratio and population size of loggerhead turtles from Southwestern Florida

Species that display temperature-dependent sex determination are at risk as a result of increasing global temperatures. For marine turtles, high incubation temperatures can skew sex ratios towards females. There are concerns that temperature increases may result in highly female-biased offspring sex ratios, which would drive a future sex ratio skew. Studying the sex ratios of adults in the ocean is logistically very difficult because individuals are widely distributed and males are inaccessible because they remain in the ocean. Breeding sex ratios (BSR) are sought as a functional alternative to study adult sex ratios. One way to examine BSR is to determine the number of males that contribute to nests. Our goal was to evaluate the BSR for loggerhead turtles (Caretta caretta) nesting along the eastern Gulf of Mexico in Florida, from 2013-2015, encompassing three nesting seasons. We genotyped 64 nesting females (approximately 28% of all turtles nesting at that time) and up to 20 hatchling...具有温度依赖型性别决定（temperature-dependent sex determination）机制的物种，正面临全球气温升高带来的生存风险。对于海龟而言，孵化期的高温会使其种群性比偏向雌性。有研究担忧，气温升高可能导致后代性比极度偏向雌性，进而引发未来种群性比失衡。然而，对海洋中成体海龟的性比开展研究的组织实施难度极大：一方面，海龟个体分布极为分散；另一方面，雄性海龟终生栖息于海洋，难以接触取样。繁殖性比（Breeding sex ratios, BSR）因此被视作研究成体性比的可行替代方案。评估繁殖性比的核心途径之一，是统计参与筑巢繁殖的雄性个体数量。本研究旨在对2013至2015年（涵盖三个筑巢季）佛罗里达州墨西哥湾东部沿岸筑巢的红海龟（Caretta caretta）的繁殖性比进行评估。研究团队对64只筑巢雌性红海龟（约占同期筑巢海龟总数的28%）以及至多20只幼龟进行了基因分型……