中文摘要：

文昌鱼是进化发育研究的重要模式动物,目前实验材料均采自野外。因此,对其进行正确的物种鉴定和地理种群的遗传分化分析十分必要。该研究扩增并测定了COXⅠ基因部分序列,结合NCBI数据库中的COXΙ序列信息,对太平洋西岸文昌鱼的种类和地理种群分化情况进行了分析。结果表明,马来文昌鱼（Branchiostoma malayanum）、白氏文昌鱼（B.belcheri）和日本文昌鱼（B.japonicum）这3个种之间的遗传差异很大,再次证实3个物种的有效性,同时提出应当审慎对待NCBI数据库中文昌鱼的种名标注;太平洋西岸文昌鱼属Branchiostoma的3种文昌鱼群体遗传多样性均处于较高水平,同一物种的不同地理种群间没有出现明显的遗传分化,反映了海洋动物的基因交流较容易,不同海域隔离较弱。

英文摘要：

Amphioxus（lancelet） is an important model animal in the field of Evo-Devo study.However,the specimens for laboratorial experiments are usually sampled directly from the field.Thus,it is necessary to correctly identify species and evaluate the genetic diversity of geographic populations.In the present investigation,we amplified and sequenced COX Ⅰ gene of amphioxus collected from various localities of the West Pacific Ocean and downloaded all available sequences of the gene from NCBI.Based on those sequences data,we constructed NJ tree to decide the taxonomic status of those amphioxus and performed AMOVA analysis to estimate genetic diversities among geographic populations and individuals.The current results supported the validity of the three amphioxus species,Branchiostoma malayanum,B.belcheri and B.japonicum.We also proposed that some amphioxus species names recorded in NCBI sequence database might be inaccurate.Genetic analysis on the geographic populations of amphioxus species suggested that each examined amphioxus species have a high level of genetic diversity.However,the genetic divergences among geographic populations of the same species are indetectable,indicating a frequent gene flow among them.