Abstract:

Species classification and identification constitute the cornerstone of biological research. Integrating DNA barcoding with classical taxonomic approaches can enhance the reliability of species identification. In this study, the traditional morphology and mitochondrial cytochrome b gene (Cyt b) sequence were employed to identify 74 zokor samples collected from Ping’an District, Haidong City, Qinghai Province, on the eastern of the Qinghai-Xizang Plateau. Based on skull morphology, individuals with sparsely coated short white hair on the tail (Pac) were identified as Eospalax cansus, whereas those with densely haired tail (Pab) were identified as Eospalax baileyi. A total of 25 Cyt b haplotypes were defined among the 74 specimens. Phylogenetic analysis based on Cyt b gene sequences of eight zokor species from GenBank showed that each species formed a well-supported monophyletic clade. The 16 haplotypes of Pab and the eight haplotypes of Pac from Ping’an District clustered within the clades of E. baileyi and E. cansu, respectively. The genetic distance between Pac and E. cansus was significantly smaller than that between Pac and other species (P < 0.001), and similarly, the distance between Pab and E. baileyi was smaller than that between Pab and other species (P < 0.001). The Cyt b identification results were consistent with those from skull morphology, confirming that the mitochondrial Cyt b is an effective DNA barcode candidate for Myospalacinae. Morphological and DNA barcoding results indicate that, two species, E. baileyi and E. cansus, are distributed in Ping’an District. Geographically, E. cansus occurs mainly at relatively low altitudes in the north, closer to the Loess Plateau, while E. baileyi is found at higher altitudes in the south, nearer the Qinghai-Xizang Plateau. This study improves our understanding of zokor species composition and distribution in Ping’an District, and provides a solution to the challenges of morphological identification in zokors through DNA barcoding.

Key words: DNA barcoding, zokor, Cyt b, Morphology, Phylogenetics, Genetic distance

摘要：

物种分类和鉴定是生物学研究的基石，综合分子生物学和经典分类学方法进行物种鉴定可提高结果可靠性。本研究采用传统形态学和线粒体细胞色素b基因（Cytb）序列对青藏高原东缘青海省海东市平安区采集的74个鼢鼠样本进行物种鉴定。头骨形态鉴定结果显示，尾巴被稀疏短白毛的鼢鼠个体（Pac）为甘肃鼢鼠（Eospalax cansus），而尾巴被密毛的个体（Pab）为高原鼢鼠（Eospalax baileyi）。74个鼢鼠样本的Cytb序列共定义了25个单倍型，结合GenBank中8种鼢鼠的Cyt b序列进行分析，在构建的系统发育树中，已知8种鼢鼠序列各自聚为1个单系群，平安区Pab的16个单倍型与已知高原鼢鼠聚为一支，Pac的8个单倍型与已知甘肃鼢鼠聚为一支。遗传距离结果显示，Pac与已知甘肃鼢鼠遗传距离小于与其他物种的遗传距离（P < 0.001），Pab与已知高原鼢鼠的遗传距离小于与其他物种的遗传距离（P < 0.001）。Cytb基因分析和形态鉴定结果一致，Cytb是鼢鼠鉴定的一个有效的DNA条形码基因。综合形态学和DNA条形码鉴定结果，平安区分布着2种鼢鼠：甘肃鼢鼠和高原鼢鼠。在地理分布上，甘肃鼢鼠主要分布在平安区北部邻近黄土高原海拔相对较低的区域，高原鼢鼠则分布在南部邻近青藏高原海拔相对较高的区域。本研究加深了对平安区鼢鼠物种组成和分布特征的了解，并为解决鼢鼠物种形态鉴定难的问题提供了DNA条形码解决方案。

关键词: DNA条形码技术, 鼢鼠, Cytb, 形态, 系统发育, 遗传距离