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大青鲨线粒体遗传变异及真鲨科的并系发育

Mitochondrial genetic variation of the blue shark (Prionace glauca) and paraphyletic evolution of the Carcharhinidae

  • 摘要: 解析渔业生物遗传变异格局对其资源管理和保护具有重要意义。大青鲨(Prionace glauca)作为一种大型中上层软骨鱼类,具有重要的生态和保护价值,然而其线粒体遗传变异格局鲜有报道。本研究采用生物信息学分析方法组装并注释舟山近海大青鲨线粒体基因组全序列,通过比较基因组学分析方法解析其线粒体遗传变异格局,同时重构了20种真鲨科鱼类的系统发育关系。新组装的大青鲨线粒体基因组全长为16 706 bp,具备典型的脊椎动物线粒体基因组特征。比较分析结果显示:①我们组装的线粒体全序列与来自希腊近海的序列首先聚为一支,揭示了大青鲨具有跨大洋的遗传同质性;②共检测到58个变异位点,其中大部分(44/58,75.87%)位于蛋白质编码基因,8个位于控制区,ND1ND4ND5等蛋白质编码基因的遗传变异性与控制区相当;③位于蛋白质编码基因的变异位点主要为同义替换,提示强烈的纯化选择作用;④基于不同数据集对20种真鲨科鱼类进行系统发育分析,结果显示真鲨属(Carcharhinus)内存在大量的系统发育冲突及并系演化关系,表明其系统发育关系的复杂性。大青鲨线粒体蛋白质编码基因存在异常高的遗传变异性,暗示其群体遗传学研究中应考虑结合NADH基因以准确评估遗传多样性水平。本研究报道的数据和结果对大青鲨渔业资源的科学管理和保护具有重要意义。

     

    Abstract: Elucidating the genetic variation patterns of fishery species is of great significance for their resource management and conservation. The blue shark (Prionace glauca), as a large pelagic migratory cartilaginous fish, has significant ecological and conservation value. However, there are few reports on its mitochondrial genetic variation pattern. In this study, we assembled and annotated the mitogenome of P. glauca collected from the coastal waters of Zhoushan, China, and conducted comparative analyses to examine its mitochondrial evolutionary patterns and phylogenetic status. Meanwhile, the phylogenetic relationships among 20 carcharhinid species were reconstructed. The newly assembled mitochondrial genome of the blue shark is 16 706 bp in length and possesses the typical features of vertebrate mitochondrial genomes. Comparative analyses revealed that: (1) The complete mitogenome assembled in this study clustered first with that from the coastal waters of Greece, indicating trans-oceanic genetic homogeneity in the blue shark; (2) A total of 58 variable sites were detected, most of which (44/58, 75.87%) were located in the protein-coding genes (PCGs), and eight were in the control region. and the genetic variability of protein-coding genes such as ND1, ND4, and ND5 was comparable to that of the control region; (3) The variable sites located in protein-coding genes were predominantly synonymous substitutions, suggesting strong purifying selection in the blue shark mitogenomes; (4) Phylogenetic analyses of 20 Carcharhinidae‌ species based on different datasets revealed extensive phylogenetic conflicts and paraphyletic relationships within the genus Carcharhinus, indicating the complexity of their phylogenetic relationships. The exceptionally high genetic variability observed in the mitochondrial protein-coding genes of the blue shark suggests that NADH dehydrogenase genes should be considered in future population genetic studies to accurately assess genetic diversity. These findings from our study provide novel implications for the management and conservation of blue shark fisheries.

     

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