甘肃省几种裂腹鱼类系统发育关系探讨

Molecular phylogeny of schizothoracinae fishes in Gansu Province based on mitochondrial cytochrome b gene sequences

通过PCR技术扩增了分布于甘肃省的裂腹鱼亚科（Schizothoracinae）5属9种鱼类的线粒体细胞色素b基因全序列（1140bp）．结果表明：Cytb基因序列的T，C，A和G碱基组成平均为25．9％，30．4％，26．9％和16．8％，共有变异位点346个，其中简约信息住点309（27．10％）．基于Kimura双参数模型计算的遗传距离结果显示几种鱼的平均遗传距离在0．014（嘉陵裸裂尻与黄河裸裂尻之间）～0．226（重口裂腹鱼与极边扁咽齿鱼之间）．用邻接法（NJ）和最大简约法（MP）构建的系统树结果均显示，同为原始等级的齐口裂腹鱼和重口裂腹鱼亲缘关系较近，同为特化等级的渭河裸重唇鱼和厚唇裸重唇鱼亲缘关系较近，聚为一支，而高度特化等级的祁连裸鲤、花斑裸鲤、嘉陵裸裂尻、黄河裸裂尻和极边扁咽齿鱼亲缘关系较近，聚为一个大的分支．依据分子进化速率推测三个类群间发生分歧的时间约在上新世晚期到更新世，伴随青藏高原隆升这一地质事件．

Totally 1 140bp complete sequence of mitochondrial cytochrome b gene of 9 species in 5 genera of Schizothoracinae fishes in Gansu province are amplified and sequenced. For the Cytb gene , the average nucleotide contents of T,C,A and G are 25. 9%,30. 4%,26. 9% and 16.8% respectively. There are 346 variable sites, of which 309 are parsimony informative sites. The results show the average Kimura 2-paramatre genetic distances among 9 species from 0. 014 （between Schizopygopsis pylzovi and Schizopygopsis kialingensis） to 0. 226（between Platypharodon extremus and Schizothorax davidi）. The molecular phylogenetic tree constructed based on the neighbor-ioining（NJ） tree and maximum parsimony （MP） tree show that all individuals divide into three clades, corresponding to the primordial-grade Schizothoracinae species, the specialized-grade Schizothoracinae species and the highly specialized-grade Schizothoracinae species, respectively. It is referred from the molecular evolution rate that the divergence of the 9 Schizothoracinae species occurred during the period from the late Pliocene to the Pleistocene with the uplift of the Qinghai-Tibet Plateau.