基于线粒体COII和ND4基因序列的塔里木裂腹鱼群体遗传多样性分析

为探究塔里木裂腹鱼群体的遗传多样性和遗传分化现状，选用车尔臣河、克孜勒河和阿克苏河3个不同地理种群的塔里木裂腹鱼共计126尾样本，进行线粒体DNA COII和ND4基因序列的对比分析，探讨了2种标记对塔里木裂腹鱼遗传多样性分析结果的差异和关系。结果显示，塔里木裂腹鱼线粒体DNA COII和ND4基因序列的A+T含量均高于G+C含量，碱基组成具有偏倚性。基于线粒体DNA COII和ND4基因序列分析，126个样本中分别确定了6个和23个单倍型，其中线粒体DNA COII基因序列中3个群体存在共享单倍型现象，线粒体DNA ND4基因序列中未发现3个群体间存在共享单倍型。2种标记下群体的单倍型多样性和核苷酸多样性分别为0.738±0.019/0.904±0.014和0.02129±0.00298/0.04876±0.00149，呈现出高单倍型多态性和高核苷酸多态性的特征。2种标记的分子方差分析（AMOVA）均表明，在所有群体中遗传变异主要来源于群体间，且车尔臣河群体的塔里木裂腹鱼与其他2个群体的遗传分化均达到显著水平（P<0.05）。贝叶斯法（BI）构建的BI树与单倍型网络图结构一致，塔里木裂腹鱼形成了2个分支。COII和ND4基因序列的岐点分布图均呈现双峰型，表明塔里木裂腹鱼现在的分布是先前分化种群发生二次交流的结果。种群结构分析结果亦表明塔里木裂腹鱼已分化出2个明显的地理种群，故建议将车尔臣河群体作为塔里木裂腹鱼的亚种。

Genetic diversity analysis of Schizothorax biddulphi based on mitochondrial DNA COII and ND4 genes

In order to explore the genetic diversity and genetic differentiation status of the Schizothorax biddulphi, three different geographic populations of the S. biddulphi in the Qarqan River, Kyzylsu River, and Aksu rivers were selected as the research objects. The mitochondrial DNA COII and ND4 gene sequences of 126 samples were compared and analyzed, and the differences and relationships between the two markers on the genetic diversity analysis results of S. biddulphi were discussed. The results showed that the A + T content of the mitochondrial DNA COII and ND4 gene sequences of S. biddulphi were higher than the G + C content, and the base composition was biased. And the base composition is biased. Based on mitochondrial DNA COII and ND4 gene sequence analysis, 6 and 23 haplotypes were identified in 126 samples. In the mitochondrial DNA COII gene sequence, there were shared haplotypes in the three populations. In the mitochondrial DNA ND4 gene sequence, no shared haplotypes were found among the three populations. There is no shared haplotype among the three populations in the mitochondrial DNA ND4 gene sequence. Based on the two markers, the haplotype diversity and nucleotide diversity of the three populations are 0.738±0.019/0.904±0.014 and 0.02129±0.00298/0.04876±0.00149, respectively. S. biddulphi is characterized by high haplotype polymorphism and high nucleotide polymorphism. The analysis of molecular variances (AMOVA) of the two markers showed that the genetic variation mainly came from the groups in all populations. and the genetic differentiation of the S. biddulphi from the Chechen River group and the other two groups reached a significant level (P <0.05). Moreover, the genetic differentiation between the Qarqan River population and the other two populations reached a significant level (P <0.05). The BI tree constructed by Bayesian method (BI) is consistent with the haplotype network diagram, and the S. biddulphi forms two branches. The Mismatch distribution of the COII and ND4 gene sequences are both bimodal pattern. This result indicates that the current distribution of S. biddulphi is the result of a second exchange between previously differentiated populations. The results of the population structure analysis also indicated that the S. biddulphi had differentiated into 2 distinct geographic populations. Therefore, it is recommended that the Qarqan River population be regarded as a subspecies of S. biddulphi.