核基因在鱼类分子系统学研究中的应用

The Applications of Nuclear Genes in Fish Molecular Systematic

利用分子标记探讨鱼类的系统发育和分子进化已经逐渐成为现代鱼类系统学研究的热点之一。本文综述了核基因在鱼类分子系统发育和分子进化研究中的应用现状及其存在的优缺点。常用的核基因主要有核糖体基因,其中保守的18SrDNA及28SrDNA主要用于研究高级分类阶元;在研究亲缘关系较近的物种以及不同地理种群时,比较常用到的则是ITSs以及SINEs;而RAGs及S7性质独特,也常被用于鱼类的分子系统学研究中。以往的研究主要利用线粒体基因(如Cytb等)研究鱼类的分类和进化,但多年来的研究发现,线粒体基因在研究鲤形目(Cypriniformes)、鲈形目(Perci-formes)等鱼类系统发育时并不能成为最佳的选择。最近的研究表明,核基因能够弥补线粒体基因的缺陷,并可广泛应用于鱼类系统发育研究。然而,核基因的应用也面临着如下问题:1)因核基因重组导致数据分析难度较大;2)鉴定不同类群时存在一定误差;3)单倍性核基因片段较难获得;4)对某些进化时间短的群体的系统发育研究效果较差。随着上述问题的逐步解决,核基因的应用将会更加广泛。

Recently, it has become one of the hotspots to study the phylogeny and molecular evolution in fish taxonomy using molecular markers. In previous researches, mitochondrial genes （mtDNA） were commonly used as molecular markers; however disadvantages existed as well. In fish molecular phylogenetic researches, nuclear genes （nDNA） can be used instead of mitochondrial genes, by which the pbylogenetic tree generates unexpected results on some occasions. In this article, we reviewed the frequentlyused nDNA and their available applications in fish molecular phylogenetic studies, as well as the existed problems and the feasible resolutions. 18S rDNA and 28S rDNA are conserved and often apply to the senior taxa, while in the study of the close phylogenetic relationship of species and different geographic group, researchers would like to choose ITSs and SINEs as molecular markers. For the further applications of nDNA, the comparison of the different usages of nDNA and mtDNA in fish phylogenetics were also compared.