Analysis On The Two Complete Mitochondrial Genomes Of Anguidae And The Phylogenetic Relationships Of Squamata

The taxa with nonexistent legs are always the research hotspot of phylogenetic studies of Squamata, such as Family Anguidae, Suborder Serpentes and Family Dibamidae. It has been proved that the complete sequence of mitochondrial genome is one of the most convincing proof on the animal phylogeny studies. Only two abroad records of the complete mt DNA sequence of Anguidae species could be found in Gen Bank so far, of which no sequence of Anguidae species was report in domestic researches yet. A total of 5 complete mt DNA sequences of herpetological species were determined in this study, which contain Ophisaurus harti, Ophisaurus gracilis, Elaphe bimaculata, Glandirana tientaiensis and Physignathus cocincinus. Meanwhile, the structure of mitochondrial genome between Ophisaurus harti and Ophisaurus gracilis were analyzed in the study. The aim of this study is to better understand the phylogenetic relationships of Squamata by using the data of complete mt DNA sequence. On basis of all the complete mt DNA sequences of Squamata in Gen Bank, the phylogenetic trees were rebuilt by the methods of BI, MP and ML respectively. Main viewpoints are demonstrated as follows:(1) The mt DNA genome structures of Ophisaurus harti and Ophisaurus gracilis were the simlar to that of typical vertebrate, of which gene rearrangement was not detected.(2) The result showed that the new genus Dopasia should be supported in Anguidae. The relationship among families in Anguimorpha could be displayed as follow:((Anguidae, Varanidae),(Shinisauridae, Helodermatidae)).(3) On the relationships among families in Squamata, the point of “ventom clade” is not supported in the present study.(4) Gekkota is monophyletic, and the divergence existed early in evolution ofSqamata. The viewpoint that Gekkota should be isolated from Squamata and regarded as a new Order is not supported in this study. The relationship among Gekkota can be described as follow:((Gekkonidae+Phyllodactylinae)+(Pygopodidae+Eublepharidae)).(5) The result agreed on the viewpoint of terrestrial origin in snakes. In Squamata, snakes had a more close relations with Iguana clade, and then constitute a sister group with Amphisbaenia.