基于线粒体Cytb和COⅠ基因对珠江、海南和红河长臀鮠群体遗传结构分析

Population genetic structure of C. multiradiatus, C. bouderius and C. henrici on the mitochondrial Cytb and COⅠsequence

为了解3个种群的野生资源状况,并对3个种群的物种有效性进行分析,采用Cytb和COⅠ基因序列测定技术,分析了珠江水系、海南水系和越南红河水系长臀鮠种群的群体遗传结构及其变异,结果发现,三个群体平均遗传距离分别为0.003(cytb)和0.002(coⅠ);94尾个体分别存在35(Cytb)和13(COⅠ)个变异位点,分别检测出24(Cytb)和13(COⅠ)个单倍型,总群体单倍型多样性(Hd)分别为0.875(Cytb)和0.787(COⅠ),平均核苷酸差异数(K)分别为3.194(Cytb)和1.328(COⅠ),核苷酸多样性指数(Pi)分别为0.00295(Cytb)和0.00213(COⅠ)。珠江长臀鮠单倍型多样性(Hd)和核苷酸多样性(Pi)最高,海南最低;对长臀鮠群体进行历史动态分析,三个种群各自无明显扩张趋于稳定,但将三个种群作为一个群体时发现长臀鮠可能在某一个时期产生了扩张。研究结果表明,三个种群遗传距离显著小于临界值2%,应为同一个种;长臀鮠野生资源较为贫乏,且海南群体最为严重。

The genetic wild resources are of critical importance to maintain the species diversity in a population. The current study aims to determine status of genetic variability and genetic structure of three Cranoglanis species （C. multiradiatus, C. bouderius and C. henrici）. We performed the species variability and historical dynamic analysis using the Cytb and CO I genes in the population of these three species. Results showed that the average genetic distance between the three populations of Cytb and CO I was 0.003 and 0.002 respectively. For Cytb sequences, the number of haplotype was 24, haplotype diversity was 0.875, the nucleotide diversity was 0.00295, the average nucleotide difference was 3.194, and the number of polymorphic site was 35. For CO I sequences, the number of haplotype was 13, the haplotype diversity was 0.787, the nucleotide diversity was 0.00213,the average nucleotide difference was 1.328, and the number of polymorphic site was 13. The C. bouderius had a higher haplotype and nucleotide diversity than the other two species of Cranoglanis. The diversity of C. multiradiatus was the lowest. Historical dynamic analysis was also carried out considering Cranoglanis as a single group but expansion was not so apparent and tended to be almost stable. The analysis result revealed that the average genetic distance was significantly lower, i.e. 〈2%, therefore, the three species might be the same. It can be concluded here that the wild resources of Cranoglanis is relatively declined and the C. multiradiatus is seriously affected.