基于Cyt b基因探讨羚羊亚科原羚属系统发生关系

原羚属物种在羚羊亚科中的分类地位尚存在很多争议。本文测定了原羚属的黄羊和藏原羚细胞色素b基因全序列(1140bp)，并与牛科其它属31个种的同源序列进行比较，对其碱基组成变异情况及核苷酸序列差异进行了分析。基于细胞色素b基因全序列，用简约法(MP)、邻接法(NJ)和似然法(ML)构建了系统进化树。结果表明：黄羊和藏原羚的序列差异为3．78％，颠换数目近乎为0，其突变远未饱和；原羚属内黄羊和藏原羚为不同种，单系发生；原羚属与赛加羚羊属、犬羚属及跳羚属等并系发生，原羚属隶属于羚羊亚科，应为独立属；羚羊亚科组成属间多为并系起源。根据序列差异值2％／百万年的细胞色素6分子钟，推测黄羊和藏原羚分歧时间大约为1～2百万年；原羚属与羚羊亚科其它属分歧时间大约在5．7～8百万年。

Molecular Phylogenetic Relationships for Procapra in Antilopinae(Artiodactyla,Bovidae) Based on Sequence of Mitochondrial Cytochrome b Gene

The phylogenetic relationships between species in genus Procapra and other genera of subfamily Antilopinae are unclear. Total DNA of Mongolian gazelle and Tibetan gazelle samples were extracted and Cyt b complete genes were sequenced (samples of the Mongolian gazelle and the Tibetan gazelle were collected from Inner Mongolian Autonomous region and Sichuan province respectively).Through comparison between the Cyt b complete gene determined in this study and those of 31 species in the family Bovidae available from GeneBank, the sequence divergence,base composition and base substitutions among these sequences were analyzed. The phylogenetic trees were constructed by most parsimonious(MP) ,neighbor-joining(NJ) and maximum-likehood (ML)methods.The bootstrap values were calculated from 1 000 replicates for MP tree and NJ tree and 100 replicates for ML tree.Our study demonstrates that the Mongolian gazelle (Procapra gutturosa) and Tibetan gazelle (Procapra picticaudata)share the closest affinity and that they occupy the basal position in the Antilopinae.Procapra is monophyletic in all analyses (MP, NJ and ML trees ).The sequence divergence between Mongolian gazelle and Tibetan gazelle was 3.78%.Phylogenetic relationship between Genera of Antilopinae are more paraphyletic than monophyletic.Base on the Cyt b molecular clock(2%/million year),the divergence time between the Mongolian and Tibetan gazelles was estimated to 1-2 million years before present and 5.7-8 million years before present between genera Procapra and others Genera of Antilopinae.