用mtDNA 12S rRNA序列变异检验鲤形目鱼类系统发育关系

通过对鲤形目鱼类5个科的代表类群的完整线粒体12S rRNA进行测序和分析，以检验目前的形态学假说。经序列比对后，有1000个位点，其中467个位点在茎区，533个在环区；有395个位点为变化位点，其中267个为系统发育信息位点。采用邻接法和最大简约法进行了系统发育分析，其结果支持鲤科鱼类成为一个单系群，非鲤科的鲤形目鱼类成为另一个单系群的观点，这与Siebert提出的假说相一致。鲤科鱼类包含3个主要的分支，即鱼丹系、鲤系和雅罗鱼系；但在非鲤科鲤形目鱼类中，其关系不能得到很好的解决，其中鳅科是复系，平鳍鳅科、条鳅亚科和花鳅亚科可能有较近的亲缘关系。

Phylogenetic Relationships of the Cypriniformes Tested by mtDNA 12S rRNA Sequence Variations

Cypriniformes is the largest order of freshwater fishes.The phylogenetic relationships of the Cypriniformes have been studied by many investigators based on morphological characters,but no agreement has been reached.In the present paper,complete mitochondrial 12S rRNA sequences of five families of the Cypriniformes were determined and analyzed to test the present morphological hypotheses.After alignment,there are 1 000 sites,among which 467 sites are in stems and 533 sites in loops.395 sites are variable,and of which 267 are informative.Neighbor-joining and Maximum Parsimony methods were employed for phylogenetic analysis.The results indicate that the cyprinids form a monophyletic group while the non-cyprinid cypriniforms form another one,which is in accordance with the hypothesis proposed by Siebert.The Cyprinidae consists of three main clades,the Danionini,the Cyprinini,and the Leuciscini.However,in the non-cyprinid cypriniforms,the relationships could not be resolved clearly.The Cobitidae is polyphyletic.Homalopteridae,Noemacheilinae and Cobitinae may have closer relationships.