重庆市城口县大巴山国家级自然保护区发现宁陕线形蛇与该物种的遗传分化分析

宁陕线形蛇Stichophanes ningshaanensis Yuan,1983是游蛇科Colubridae的单型属单型种,为中国特有种,至今仅被报道分布于陕西省宁陕县火地塘(模式产地)、湖北省神农架国家级自然保护区和重庆市五里坡国家级自然保护区。目前对该物种的研究和野外采集记录甚少。2017年7月8日,在重庆市城口县大巴山国家级自然保护区采到1号疑似宁陕线形蛇的雌性成体标本。经形态比较和分子系统发育分析,鉴定为宁陕线形蛇。基于线粒体细胞色素b(cyt b)基因和核基因片段cmos的系统发育分析表明,城口大巴山标本嵌入宁陕线形蛇支系中,与该物种其他种群在cyt b基因上的遗传距离(0.001~0.009)远小于与其近缘种的(0.174~0.292)。本研究揭示宁陕线形蛇种群间存在形态和遗传上的分化。形态上,城口大巴山标本上唇鳞数量为5/5,而神农架和火地塘种群均为6/6,前者尾下鳞数量为61对,少于后者(64~73对)。在cyt b基因上,3个种群各自拥有1个单倍型。城口大巴山单倍型与湖北神农架单倍型之间有1个突变、与宁陕火地塘单倍型之间有9个突变,而分子系统树支持宁陕火地塘种群与湖北神农架种群关系更近。研究结果为宁陕线形蛇的地理分布和系统学研究提供了重要信息。

Discovery of Stichophanes ningshaanensis in Dabashan National Nature Reserve,Chengkou County,Chongqing City,with Intraspecific Genetic Divergence of the Species

Stichophanes ningshaanensis Yuan,1983,which belonging to the monotypic genus Stichophanes of the family Colubridae,is endemic to China.To present,this species was only known to be distributed in Huoditang,Ningshaan county,Shaanxi province,Shennongjia National Nature Reserve,Hubei province,and Wulipo National Nature Reserve,Chongqing city.Few studies have been focused on this species due to the lack of wild specimens.On July 8,2017,one female specimen presented similar morphological features with S.ningshaanensis was collected from Dabashan National Nature Reserve(Chengkou county,Chongqing city).Based on sequence data of mitochondrial cyt b gene and nuclear gene cmos,the results of phylogenetic analyses suggested that this specimen was clustered together with the specimens from the other 2 known populations,which were clustered into a monophyly corresponding to S.ningshaanensis.Genetic distance between the 3 populations of the species was 0.001-0.009,which was significantly smaller than that between the species and its related species(0.174-0.292).Moreover,there was considerable divergence among different populations of this species.On morphology,the specimen from Dabashan had only 5 supralabials on both sides and 61 pairs of subcaudals,while the others had 6 supralabials and 64-73 pairs of subcaudals.On cyt b gene,the 3 populations occupied distinct haplotypes.There was a mutation between the haplotypes from Chengkou county and Shennongjia,Hubei province,while 9 mutations were detected between haplotypes from Chengkou county and Huoditang,Ningshaan county.However,phylogenetic analyses suggested that Shennongjia population was closer to Huoditang population.This study provides a basis for future investigations on the distribution and systematics of Stichophanes species.