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基于线粒体DNA COⅠ和控制区序列的中国鱚群体遗传多样性分析

Population genetic diversity analysis of Sillago sinica based on mitochondrial DNA COⅠgene and D-loop sequence

  • 摘要: 鱚科鱼类是我国重要的海洋经济物种,中国鱚(Sillago sinica)作为该科鱼类中的新发现种,查明其遗传变异特征和演化格局可为科学制定资源管理政策提供参考依据。为此,本研究选取了两个线粒体序列片段(COⅠ基因和D-loop区)作为分子标记,对4个中国鱚群体(青岛、乳山、嵊泗和温州)遗传多样性和遗传结构进行了研究。通过PCR扩增和比对后得到长度为614 bp (COⅠ)和458 bp (D-loop)的序列片段,分别检测到11个和13个变异位点,定义了7种和9种单倍型,且存在单倍型共享现象。基于D-loop区序列得到4个群体的平均单倍型多样度和核苷酸多样度(0.452、0.00260)略高于COⅠ基因(0.142、0.00044),均表现为较低的遗传多样性水平。中国鱚不同群体间遗传距离为0.000130.00062 (COⅠ)和0.001770.00350 (D-loop),遗传分化指数和分子方差分析显示遗传变异主要源自群体内。邻接系统进化树大致呈现出南北不同海域分布格局的特点,即分布于黄海的青岛、乳山群体(北方组群)和分布于东海的嵊泗、温州群体(南方组群)分别聚类。群体历史动态分析表明北方组群的中国鱚可能经历了群体扩张事件,而南方组群数量规模相对稳定,未产生大幅波动。综上所述,中国近海中国鱚群体遗传多样性低,不同海区之间呈现显著的遗传差异,需要划定不同的渔业单元进行单独管理。

     

    Abstract: Sillaginidae is an important marine economic fish in China. Sillago sinica is a newly recorded species in this family, identifying its genetic characteristics and phylogenic pattern can provide references for rational fishery resource management. The mitochondrial COⅠgene and D-loop region were used as molecular markers to explore genetic diversity and genetic structure of four S. sinica populations (Qingdao, Rushan, Shengsi and Wenzhou) in coastal waters of China. The lengths of 614 bp (COⅠ) and 458 bp (D-loop) fragments were obtained after the polymerase chain reaction (PCR) and sequence alignment. A total of 11 and 13 polymorphic loci were detected based on COⅠgene and D-loop region, defining 7 and 9 haplotypes, respectively. Also, the shared haplotypes were identified among different populations. The average haplotype diversity (Hd) and nucleotide diversity (π) of D-loop region were 0.452 and 0.00260, which were slightly higher than those of COⅠgene (0.142 and 0.00044), indicating relatively low levels of genetic diversity. The genetic distances of different populations ranged from 0.00013 to 0.00062 (COⅠ) and from 0.00177 to 0.00350 (D-loop), respectively. The genetic differentiation index (Fst) and analysis of molecular variance (AMOVA) suggested that the majority of genetic variation resided within the populations. The neighbor-joining (NJ) tree showed geographical distribution patterns from the southern and northern sea areas. Qingdao and Rushan populations distributing in the Yellow Sea clustered together, while Shengsi and Wenzhou populations belonging to the East China Sea formed an independent clade. The analysis of population demographic history implied that S. sinica from the northern group might have experienced a population expansion event. However, the number and scale of S. sinica from the southern group were relatively stable with no obvious fluctuations. In summary, low genetic diversity together with significant genetic differences between divergent sea areas indicated that different fishery units of S. sinica should be managed separately in China.

     

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