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利用PCR技术扩增得到珠江和长江水系共29个赤眼鳟(Squaliobarbus curriculus)线粒体DNA D-loop基因片段,并测定其序列。对599 bp的D-loop基因序列进行分析,共检测到24个单倍型,25个单突变位点,39个简约信息位点。在81个突变位点中,转换位点50个,颠换位点14个,插入或缺失位点17个;A+T的含量(68.8%)明显高于C+G的含量(31.2%)。5个水域个体间的遗传变异率在0到6.03%之间。单倍型多样性(H)为0.977 8,平均核苷酸差异数(K±SD)为17.271 0,核苷酸多样性(π)为0.029 7。对5个群体D-loop序列进行分化指数分析,结果表明:不同水系群体间有显著的遗传差异,而同一水系内的不同群体间差异不显著。对5个群体进行分子方差分析,结果表明:5个群体间存在显著性遗传差异。分子系统树显示:两大水系5个不同水域赤眼鳟29个个体的系统树明显分为两支:珠江15个个体聚为一支,长江14个个体聚为另一支,且都有较高的置信度。可见,长江和珠江群体间已经出现了明显的遗传变异,是因珠江和长江的地理隔离导致的生殖隔离。但在同一水系内,群体间的遗传距离和群体内的遗传差异不显著,系统树也是两大水系内的不同水域混杂在一起,说明同一水系不同水域间没有出现遗传分化,分属“长江群体”或“珠江群体”。
A total of 29 mitochondrial DNA D-loop gene fragments were amplified from 29 Squaliobarbus curriculus populations in the Pearl River and the Yangtze River by PCR and their sequences were determined. The D-loop gene sequence of 599 bp was analyzed, 24 haplotypes, 25 single mutation sites and 39 parsimony informative sites were detected. Among the 81 mutant loci, 50 were translocation sites, 14 were transversion sites and 17 were inserted or deleted. The content of A + T (68.8%) was significantly higher than that of C + G (31.2%). . The genetic variation among individuals in 5 waters ranged from 0 to 6.03%. The haplotype diversity (H) was 0.977 8, the average nucleotide difference (K ± SD) was 17.271 0, and the nucleotide diversity (π) was 0.029 7. Differentiation index analysis of D-loop sequences showed that there were significant genetic differences among different water system populations, but no significant differences among different groups within the same water system. The molecular variance analysis of five populations showed that there were significant genetic differences among the five populations. The molecular phylogenetic tree showed that the phylogenetic tree of 29 individuals of five species of red-eye trout in five major watersheds was clearly divided into two branches: 15 individuals in the Pearl River clustered into one and 14 individuals in the Yangtze River clustered in the other and all had higher Confidence. It can be seen that obvious genetic variation has emerged between the Yangtze River and Pearl River populations and is caused by the geographical isolation of the Pearl River and the Yangtze River. However, within the same water system, the genetic distance among groups and the genetic differences within the population were not significant. The system tree was also mixed with different waters in the two major water systems, indicating that there was no genetic differentiation among different waters in the same water system, Group “or ” Pearl River Group ".