Data from: Genetic diversity of white sharks, Carcharodon carcharias, in the northwest Atlantic and southern Africa

The white shark, Carcharodon carcharias, is both one of the largest apex predators in the world and among the most heavily protected marine fish. Population genetic diversity is in part shaped by recent demographic history and can thus provide information complementary to more traditional population assessments, which are difficult to obtain for white sharks and have at times been controversial. Here, we use the mitochondrial control region and 14 nuclear-encoded microsatellite loci to assess white shark genetic diversity in 2 regions: the Northwest Atlantic (NWA, N = 35) and southern Africa (SA, N = 131). We find that these 2 regions harbor genetically distinct white shark populations (Φ ST = 0.10, P < 0.00001; microsatellite F ST = 0.1057, P < 0.021). M-ratios were low and indicative of a genetic bottleneck in the NWA (M-ratio = 0.71, P < 0.004) but not SA (M-ratio = 0.85, P = 0.39). This is consistent with other evidence showing a steep population decline occurring in the mid to late 20th century in the NWA, whereas the SA population appears to have been relatively stable. Estimates of effective population size ranged from 22.6 to 66.3 (NWA) and 188 to 1998.3 (SA) and evidence of inbreeding was found (primarily in NWA). Overall, our findings indicate that white population dynamics within NWA and SA are determined more by intrinsic reproduction than immigration and there is genetic evidence of a population decline in the NWA, further justifying the strong domestic protective measures that have been taken for this species in this region. Our study also highlights how assessment of genetic diversity can complement other sources of information to better understand the status of threatened marine fish populations.

大白鲨（Carcharodon carcharias）既是全球体型最大的顶级捕食者之一，也是受保护程度最高的海洋鱼类类群之一。种群遗传多样性在一定程度上由近期种群人口统计学历史塑造，因此可提供与传统种群评估互补的信息；而针对大白鲨的传统种群评估往往难以开展，且曾多次引发争议。本研究借助线粒体控制区（mitochondrial control region）与14个核编码微卫星（microsatellite）位点，对两个区域的大白鲨遗传多样性展开分析：西北大西洋（NWA，n=35）与南非海域（SA，n=131）。研究发现这两个区域的大白鲨种群存在显著遗传分化（Φ_ST = 0.10, P < 0.00001；微卫星F_ST = 0.1057, P < 0.021）。M比率偏低，提示西北大西洋种群存在遗传瓶颈（M-ratio = 0.71, P < 0.004），而南非种群未出现该特征（M-ratio = 0.85, P = 0.39）。该结果与其他证据一致：20世纪中后期西北大西洋大白鲨种群曾出现剧烈种群衰退，而南非种群数量相对稳定。有效种群大小的估算值范围为：西北大西洋种群22.6~66.3，南非种群188~1998.3；同时研究发现种群存在近交现象，其中以西北大西洋种群最为显著。综上，本研究结果表明，西北大西洋与南非海域的大白鲨种群动态更多由内在繁殖过程而非种群迁入决定；同时遗传证据证实西北大西洋种群出现衰退，进一步印证了该区域针对该物种实施的严格本土保护措施的合理性。本研究同时凸显了遗传多样性评估可与其他信息来源互补，以更好地了解受威胁海洋鱼类种群的生存现状。