鳗鲡目鱼类线粒体蛋白质编码基因易位及系统演化关系分析

Eels mitochondrial protein-coding genes translocation and phylogenetic relationship analyses

鳗鲡目鱼类线粒体基因组的基因组成较为保守,在58个线粒体基因组中,仅有3个物种存在基因数量的差异。在19个鳗鲡目鱼类线粒体基因组中存在主编码基因的重排。主编码基因的变异位点分析结果支持nad5、nad4和nad2基因作为cox1和lrRNA基因辅助的分子标记。鳗鲡科Anguillidae的20个种(亚种)聚在一起,强烈支持鳗鲡科为单系群(BPP=100)。鳗鲡科下属的3个类群(大洋洲类群、大西洋类群和印度洋-太平洋类群)也同时得到有力的验证(BPP均为100)。线鳗科Nemichthyidae和锯齿鳗科Serrivomeridae亲缘关系最近,二者聚类后,与鳗鲡科Anguillidae构成姊妹群(BPP=100)。在囊喉鱼亚目Saccopharyngoidei中,宽咽鱼科Eurypharyngidae与囊鳃鳗科Saccopharyngidae聚类(BPP=100),同时,单颌鳗科Monognathidae与月尾鳗科Cyematidae聚类(BPP=100),4个科聚在一支,支持囊喉鱼亚目为单系群(BPP=100)。在囊喉鱼亚目线粒体基因组中,3个物种(吞鳗Eurypharynx pelecanoides、拉文囊鳃鳗Saccopharynx lavenbergi和杰氏单颌鳗Monognathus jesperseni)存在主编码基因的重排。16种鳗鲡(细美体鳗Ariosoma shiroanago、短吻颈鳗Derichthys serpentinus、凯氏短尾康吉鳗Coloconger cadenati、鸭颈鳗Nessorhamphus ingolfianus、龟草鳗Thalassenchelys sp.、粗犁齿海鳗Cynoponticus ferox、百吉海鳗Muraenesox bagio、巨斑花蛇鳗Myrichthys maculosus、大吻沙蛇鳗Ophisurus macrorhynchos、几内亚副康吉鳗Paraconger notialis、哈氏异康吉鳗Heteroconger hassi、小头鸭嘴鳗Nettastoma parviceps、弱头鳗Leptocephalus sp.、斑点长犁齿鳗Hoplunnis punctata、尖吻小鸭嘴鳗Facciolella oxyrhyncha和星康吉鳗Conger myriaster),与鳗鲡目线粒体主编码基因的原始排列相比,共享nad6基因的易位。同时,基于线粒体基因组13个蛋白质编码基因构建的系统演化树,强烈支持这16个物种聚为一支(BPP=100)。然而,由此而带来的海鳗科Muraenesocidae、拟鯙科Chlopsidae和糯鳗科Congridae是否为单系群的问题,值得今后深入探究。

The gene composition of eels mitochondrial genomes is conservative. In 58 mitochondrial genomes, only three ones exist differences of gene number. There are major encoding gene rearrangements in 19 eels mitochondri- al genomes. The mutation sites analyses of major encoding genes support that nad5 ,nad4 and nad2 genes are ideal assistant markers to cox1 and IrRNA genes. Twenty species （subspecies） from Anguillidae are clustered together, which strongly support that the family Anguillidae is a monophyletic group （BPP= 100）. Three groups （Oceanian group, Atlantic group and the Indo-Pacific group） from Anguillidae are also strong verified （BPP of all three elades are 100）. There are closest relationship between Nemichthyidae and Serrivomeridae, and they clustering with a sister group Anguillidae （BPP= 100）. In the suborder Saccopharyngoidei, Eurypharyngidae is clustering with Sac- eopharyngidae （BPP=100）. Meanwhile, Monognathidae is clustering with Cyematidae （BPP= 100）,four families are clustered together, which strongly support that the suborder Saccopharyngoidei is one monophyletic group （BPP = 100）. Within the suborder Saccopharyngoidei, there are major encoding gene rearrangements in three species （Eurypharynx pelecanoides, Saccopharynx lavenbergi and Monognathus jesperseni ） mitochondrial genomes. Six- teen eels （ Ariosorna shiroanago , Derichthys serpentinus , Coloconger cadenati , Nessorhamphus ingol fianus , Thalassenchelys sp. , Cynoponticus f ero3c , Muraenesox bagio , Myrichthys rnaculosus , Ophisurus macrorhynchos , Paraconger notialis , Heteroconger hassi , Nettastorna parviceps , Leptocephalus sp. , Hoplunnis punctata , Facci- olella oxyrhyncha and Conger rnyriaster） share translocation of nad6 gene, which compared with the Anguilli- formes mitochondrial original arrangement. Phylogenetic tree based on the 13 mitochondrial protein-coding genes also strongly support the clustering of them （BPP= 100）. As a result, however, whether Muraenesocidae,Chlopsi- dae and Congridae are monophyletie groups or not, which worthy of further exploration.