Sequencing And Phylogenetic Analysis On Complete Mitochondrial Genome Of Three Subterranean Rodents Species

In this thesis, Long-PCR amplification and primer walking methods were used in sequencing the complete mitochondrial genome of three subterranean rodents, Lasiopodomys mandarinus, Myospalax psilurus and Myospalax baileyi. The taxonomic statuses of these rodents are still in dispute. Then bio informatics software was employed in analyzing the gene content, and organization of the mtDNA, phylogenetic position of three rodents was also analyzed.The length of the mtDNA of L. mandarinus, M. psilurus and M. baileyi were16367bp,16351bp,16360bp. The three mtDNA had a typical gene content of13protein coding genes,22tRNA genes and2rRNA genes, which were highly conserved among most rodents. Except for the eight tRNA and one ND6genes, all other mtDNA genes were encoded on the heavy strand. Like the other rodents mtDNA, the base usage of the three mtDNA also followed the A+T>C+G rule. The A+T content of L. mandarinus mtDNA was close to genus Microtus, Proedromys and Eothenomys, and two zokor’s mtDNA A+T content were close to genus Nannospalax. The codons usage, use of incomplete stop codons, tRNASer secondary structure lost its DHU arm, structures of D-loop and rep-origin were similar to other rodents’ mtDNA. The phylogenetic analysis based on13protein coding genes,2rRNA genes and Cytb genes were constructed. Phylogenetic analysis with the support of morphology data showed that L. mandarinus was one of the species of Lasiopodomys, which had a close relationship with rodents in genus Microtus, Proedromys. And the Lasiopodomys should be retained as a separated genus of Cricetidae. Two zokors were species of genus Myospalax, and the genus Myospalax and Nannospalax were two genus of Spalacidae. The phylogenetic analysis also gave further evidence for the notion of Rodentia monophyly. Compared with non-subterranean rodents, the mtDNA of three subterranean rodents didn’t show any differences in length, structures and base composition, and the phylogenetic analysis also didn’t have any fluctuations. So we suggest that the mtDNA of subterranean rodents didn’t obtain any mutations under the different environments during long-term evolution.