Genetic diversity and taxonomic status of Gymnocypris chilianensis based on the mitochondrial DNA D-loop region

To analyse the genetic diversity and taxonomic status of <i>Gymnocypris chilianensis</i>, <i>D-loop</i> region of the mitochondrial DNA was sequenced in 50 individuals of <i>G. chilianensis</i> obtained from two geographic locations (Heihe River and Shule River) and 25 individuals of <i>G. przewalskii</i>. These samples were analyzed for genetic diversity and sequence divergence, and 25 homologous sequences of another affinity <i>G. eckloni</i> downloaded from GenBank were analyzed. The results revealed that <i>G. chilianensis</i> of the Shule River showed lower haplotype diversity (Hd = 0.963) as well as nucleotide diversity (Pi = 0.00414) than the other populations, indicating that <i>G. chilianensis</i> of the Shule River should be protected preferentially due to its lower level of genetic diversity. The study also demonstrated the genetic distance of <i>G. chilianensis</i> in both Heihe River and Shule River was 0.0013, and the genetic distances between the aforementioned two populations and the <i>G. przewalskii</i> were 0.0143 and 0.0137, respectively. The genetic distances between the two <i>G. chilianensis</i> populations and the <i>G. eckloni</i> were 0.0148 and 0.0141, respectively. The NJ phylogenetic trees showed that <i>G. chilianensis</i> had further genetic distance with <i>G. eckloni</i> and <i>G. przewalskii</i>. Therefore, <i>G. chilianensis</i> could be considered as an independent species of <i>Gymnocypris</i>.

为分析祁连裸鲤（Gymnocypris chilianensis）的遗传多样性与分类学地位，本研究对采自两个地理种群（黑河与疏勒河）的50尾祁连裸鲤样本，以及25尾普氏裸鲤（Gymnocypris przewalskii）样本的线粒体DNA D-loop区进行了测序。同时纳入从GenBank数据库下载的另一个近缘种埃克伦裸鲤（Gymnocypris eckloni）的25条同源序列开展分析。随后对所有样本进行遗传多样性与序列分歧分析。结果显示，疏勒河种群的祁连裸鲤单倍型多样性（Hd=0.963）与核苷酸多样性（Pi=0.00414）均低于其他种群，提示该种群因遗传多样性水平较低，应优先开展保护。本研究还发现，黑河与疏勒河的祁连裸鲤种群间遗传距离为0.0013；二者与普氏裸鲤的遗传距离分别为0.0143与0.0137；两个祁连裸鲤种群与埃克伦裸鲤的遗传距离则分别为0.0148与0.0141。邻接（NJ）系统发育树分析表明，祁连裸鲤与埃克伦裸鲤、普氏裸鲤的遗传距离相对较远。综上，祁连裸鲤可被视为裸鲤属（Gymnocypris）的一个独立物种。