社鼠和针毛鼠线粒体DNA序列的歧异及其系统进化关系

社鼠和针毛鼠是有着广泛地理分布的山地鼠种,它们的一些形态特征及核型明显有别于同属的其它鼠类.社鼠的亚种--雷琼社鼠局限于分布在广东省西部地区和海南省,它的形态特征多似社鼠,但也有少数特征相似于针毛鼠.对于社鼠和针毛鼠的分类地位及社鼠亚种的分化一直有着各种讨论.本研究进行了社鼠和雷琼社鼠以及针毛鼠龙门种群和香港种群的细胞色素b (264个核苷酸位点)和12S rRNA (387个核苷酸位点)基因片段的测序.社鼠与雷琼社鼠线粒体的细胞色素b基因片段间包含有19个变异位点、12S rRNA 基因片段间包含11个变异位点和2个插入/缺失位点.针毛鼠的2个种群间的细胞色素b 和12S rRNA 基因片段分别包含了3个和11个变异位点.通过邻接法和最大简约法重建的系统进化关系表明:雷琼社鼠与社鼠有着紧密的亲缘关系,它的亚种地位得到了线粒体DNA序列证据的肯定.针毛鼠龙门种群和香港种群细胞色素b和12S rRNA 基因片段序列的歧异反映出两个种群由于长期的地理隔离及其所经历自然选择的结果.

Divergence of Mitochdrial DNA Sequence and Phylogenetic Relationships of Rattus confucianus and Rattus fulvescens

R. confucianus and R.fulvescens are the mountain murines with widely geographic distribution. R. c. lotipes is restrictedly distributed in the west region of Guangdong province and Hainan province. The karyotypic and some of their morphological characteristics differ from the other species in genus Rattus. The most of morphological characteristics of subspecies R. c. lotipes are identical to R. confucianus, but few features are similar to R. fulvescens. The various opinions have been in the discussions for the classification positions of R. fulvescens and R. confucianus, and the subspecies differentiation of R. confucianus. In this study, the sequences of mitochondrial cytochrome b (Cyt b) and 12S rRNA gene fragments were detected. The Cyt b and 12S rRNA gene fragments between R. confucianus and its subspecies R. c. lotipes separately include 19 variable sites and 11 variable sites. 2 sites of insertion/deletion in the 12S rRNA fragment are observed. The Cyt b and 12S rRNA fragments between two populations of R. fulvescens separately include 3 variable sites and 11 variable sites. This analysis shows that R. c. lotipes is closer to R. c. confucianus than to R. fulvescens. The position of this subspecies is confirmed by the data of mtDNA. The sequences divergences in Cyt b and 12S rRNA gene between Longmen and Hong Kong populations of R. fulvescens reflect the natural selection for their history of geographic isolation.