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（G. przewalskii）样本的线粒体DNA D-loop区进行了测序；同时对从GenBank数据库下载的25条近缘种花斑裸鲤（G. eckloni）的同源序列开展了遗传多样性与序列分歧度分析。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，表明疏勒河祁连裸鲤种群因遗传多样性水平较低，应优先实施保护。本研究同时发现，黑河与疏勒河两个祁连裸鲤种群的遗传距离均为0.0013；上述两个种群与普氏裸鲤的遗传距离分别为0.0143和0.0137，二者与花斑裸鲤的遗传距离则分别为0.0148和0.0141。邻接（NJ）系统发育树结果表明，祁连裸鲤与花斑裸鲤、普氏裸鲤的遗传距离更远。综上，祁连裸鲤可被视为裸鲤属（Gymnocypris）下的一个独立物种。