Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Stellenbosch, 7600, South Africa.
Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, 2006, South Africa.
Sci Rep. 2020 Oct 21;10(1):17959. doi: 10.1038/s41598-020-75044-2.
Knowledge about the demographic histories of natural populations helps to evaluate their conservation status, and potential impacts of natural and anthropogenic pressures. In particular, estimates of effective population size obtained through molecular data can provide useful information to guide management decisions for vulnerable populations. The spotted ragged-tooth shark, Carcharias taurus (also known as the sandtiger or grey nurse shark), is widely distributed in warm-temperate and subtropical waters, but has suffered severe population declines across much of its range as a result of overexploitation. Here, we used multilocus genotype data to investigate the demographic history of the South African C. taurus population. Using approximate Bayesian computation and likelihood-based importance sampling, we found that the population underwent a historical range expansion that may have been linked to climatic changes during the late Pleistocene. There was no evidence for a recent anthropogenic decline. Together with census data suggesting a stable population, these results support the idea that fishing pressure and other threats have so far not been detrimental to the local C. taurus population. The results reported here indicate that South Africa could possibly harbour the last remaining, relatively pristine population of this widespread but vulnerable top predator.
有关自然种群的人口统计学历史的知识有助于评估其保护状况以及自然和人为压力的潜在影响。特别是，通过分子数据获得的有效种群大小估计值可以为脆弱种群的管理决策提供有用信息。斑点锯齿鲨（Carcharias taurus）（也称为砂虎或灰护士鲨）广泛分布于暖温带和亚热带水域，但由于过度捕捞，其分布范围的大部分地区的种群数量严重减少。在这里，我们使用多基因座基因型数据来研究南非 C. taurus 种群的人口统计学历史。使用近似贝叶斯计算和基于似然的重要抽样，我们发现该种群经历了历史范围的扩展，这可能与晚更新世期间的气候变化有关。没有证据表明最近有人为下降。结合表明种群稳定的普查数据，这些结果支持这样的观点，即捕捞压力和其他威胁迄今为止尚未对当地 C. taurus 种群造成不利影响。这里报告的结果表明，南非可能拥有这种广泛但脆弱的顶级掠食者的最后一个相对原始的种群。
