从线粒体Cyt b基因探讨红瘰疣螈物种地位的有效性

疣螈属的红瘰疣螈(Tylototriton shanjing)和棕黑疣螈(T.verrucosus)的物种界限一直不清楚。测定了来自中国西南地区14个地点的T.shanjing和T.verrucosus共40只标本的线粒体DNACytb基因(753bp)。结果表明:(1)用邻接法、最大简约法和贝叶斯法等3种系统发育分析法分别重建棕黑疣螈种组系统发育树的拓扑结构不支持T.shanjing是单系群;(2)T.shanjing与T.verrucsus的mtDNA Cytb序列差异平均值仅为1.2%,未达到种级水平。因此,全部T.shanjing样品都属于同一个物种,即T.verrucosus,不支持T.shanjing的物种地位,T.shanjing为T.verrucosus的同物异名,并建议恢复T.verrucosus的中文名红瘰疣螈。根据基于40个样品Cyt b基因序列的系统发育树和遗传变异以及地理分布,这些红瘰疣螈(T.verrucosus)样品聚为3支,即中国西南地区的红瘰疣螈可分为片马、滇中滇西和滇东南3个地理居群。

The Validity of Red Knobby Newt (Tylototriton shanjing) Species Status Based on Mitochondrial Cyt b Gene

The delimitation between Tylototriton shanjing and T.verrucosus was not clear. Forty individuals of T.verrucosus and T.shanjing were collected from fourteen localities in Southwest China and 753 bp of partial mitochondrial Cyt b gene sequence were sequenced. Molecular phylogenetic trees of T.verrucosus group were reconstructed using neighbor-joining, maximum parsimony and Bayesian inference methods. Pairwise sequence comparisons to determine the amount of variation were performed using MEGA 3.0 software. According to the results of phylogeny analysis and Kimura 2-parameter distance, the species validities were evaluated. The results showed that: (1) the T.shanjing did not form a monophyletic group; (2) the genetic distance was low between T.shanjing and T.verrucosus, it was only 1.2% on average. Therefore, T.shanjing as a valid species is not supported and can be argued to be a synonym of T.verrucosus. According to our phylogenetic tree, the genetic divergences and geographic distribution, T.verrucosus' distribution in the Yunnan Province can be divided into three geographic groups, i.e. the Pianma group, the Middle and West Yunnan group and the Southeast Yunnan group.