Complete MtDNA Analysis Of The Microhyla Ornata And Rana Plancyi, And Implication For Anura Groups Phylogeny

In animals, mitochondrial DNA (mtDNA) is generally a 15-22 kb circular genome containing 37 genes: 13 protein-coding genes, two rRNA genes, and 22 tRNA genes, as well as a control region. All 37 genes are arranged in the same relative order almost in all vertebrate species from teleost fishes to eutherian mammals. In recent years, mtDNA has been widely used as a useful marker system in numerous phylogenetic analyses in vertebrate relationships.In Anura, the phylogenetic relationships among the main lineages remained largely debated. Several alternative phylogenetic hypotheses based on morphological and molecular characters have been proposed without reaching a consensus. To discuss this issue, the complete mitochondrial genome of Microhyla ornata and Rana plancyi had been sequenced in this text.The complete nucleotide sequence of the mitochondrial genome of Microhyla ornata is 16 730 bp in length, including 37 typical mitochondrial genes: 13 protein-coding genes, two rRNA genes, and 22 tRNA genes, as well as a control region. The complete nucleotide sequence of the mitochondrial genome of Rana plancyi is 17 822 bp in length, which also included 37 typical mitochondrial genes. They were the same in gene arrangement, but differed by four tRNA gene positions (tRNA-Leu(CUN)/tRNA-Thr/tRNA-Pro/tRNA-Phe) from that of typical mitochondrial in vertebrates. Furthermore, the gene arrangements were compared with other Anuras and the Tandem duplication followed by random gene loss (TDRL) model was implemented to explain for it.In this study, we discussed the phylogenetic relationships in the Anura groups with the sequences of the 12 proteins encoded in the H-strand and 22 tRNAs of mtDNA from 21 species from GenBank. They all indicated that Anura were divided into the Archaeobatrachia (group A) and the Neobatrachia (group B),these results supported the monophyletic origin of Anura. Besides,the results showed that there were 8 gene rearrangements in 21 species of Anura. The application to phylogenesis of gene rearrangement of mtDNA in Anura groups was analyzed. It showed that the higher Anura was, the more complicated gene rearrangement became.