Bernard Andrea M, Mehlrose Marissa R, Finnegan Kimberly A, Wetherbee Bradley M, Shivji Mahmood S
Save Our Seas Foundation Shark Research Center, Halmos College of Arts & Sciences Nova Southeastern University Dania Florida USA.
Guy Harvey Research Institute, Halmos College of Arts & Sciences, Nova Southeastern University Dania Florida USA.
Evol Appl. 2025 Jan 22;18(1):e70071. doi: 10.1111/eva.70071. eCollection 2025 Jan.
Large-bodied pelagic sharks are key regulators of oceanic ecosystem stability, but highly impacted by severe overfishing. One such species, the shortfin mako shark (), a globally widespread, highly migratory predator, has undergone dramatic population reductions and is now Endangered (IUCN Red List), with Atlantic Ocean mako sharks in particular assessed by fishery managers as overfished and in need of urgent, improved management attention. Genomic-scale population assessments for this apex predator species have not been previously available to inform management planning; thus, we investigated the population genetics of mako sharks across the Atlantic using a bi-organelle genomics approach. Complete mitochondrial genome (mitogenome) sequences and genome-wide SNPs from sharks distributed across the Atlantic revealed contrasting patterns of population structure across marker types. Consistent with this species' long-distance migratory capabilities, SNPs showed high connectivity and Atlantic panmixia overall. In contrast, there was matrilineal population genetic structure across Northern and Southern Hemispheres, suggesting at least large regional-scale female philopatry. Linkage disequilibrium network analysis indicated that makos possess a chromosomal inversion that occurs Atlantic wide, a genome feature that may be informative for evolutionary investigations concerning adaptations and the global history of this iconic species. Mitogenome diversity in Atlantic makos was high compared to other elasmobranchs assessed at the mitogenome level, and nuclear diversity was high compared to the two other, highly migratory pelagic shark species assessed with SNPs. These results support management efforts for shortfin makos on at least Northern versus Southern Hemisphere scales to preserve their matrilineal genetic distinctiveness. The overall comparative genetic diversity findings provide a baseline for future comparative assessments and monitoring of genetic diversity, as called for by the United Nations Convention on Biological Diversity, and cautious optimism regarding the health and recovery potential of Atlantic shortfin makos if further population declines can be halted.
大型远洋鲨鱼是海洋生态系统稳定性的关键调节者，但受到严重过度捕捞的极大影响。其中一个物种，即灰鲭鲨（），是一种全球分布、高度洄游的捕食者，其种群数量已急剧减少，目前被列为濒危物种（世界自然保护联盟红色名录），特别是大西洋的灰鲭鲨被渔业管理人员评估为过度捕捞，急需得到更好的管理关注。此前尚未有针对这种顶级捕食者物种的基因组规模的种群评估来为管理规划提供信息；因此，我们采用双细胞器基因组学方法研究了大西洋海域灰鲭鲨的种群遗传学。来自大西洋各地鲨鱼的完整线粒体基因组（mitogenome）序列和全基因组单核苷酸多态性（SNPs）揭示了不同标记类型下种群结构的对比模式。与该物种的长距离洄游能力一致，SNPs总体上显示出高连通性和大西洋全域混交。相比之下，南北半球存在母系种群遗传结构，这表明至少在大区域尺度上存在雌性偏祖现象。连锁不平衡网络分析表明，灰鲭鲨拥有一个在整个大西洋都存在的染色体倒位，这一基因组特征可能有助于对该标志性物种的适应性和全球历史进行进化研究。与在mitogenome水平评估的其他软骨鱼类相比，大西洋灰鲭鲨的mitogenome多样性较高，与另外两种用SNPs评估的高度洄游的远洋鲨鱼物种相比，其核多样性也较高。这些结果支持至少在南北半球尺度上对灰鲭鲨进行管理，以保护其母系遗传独特性。总体的比较遗传多样性研究结果为未来按照《联合国生物多样性公约》要求进行的遗传多样性比较评估和监测提供了基线，并且如果能够阻止种群数量的进一步下降，对于大西洋灰鲭鲨的健康状况和恢复潜力持谨慎乐观态度。
