Molecular Evolution And Phylogeny Of Some Species Of Eodorcadion Based On Cytb Gene Sequence

Longicorn beetles are important pests and economical insects, which play a signigicant role in forest and meadow. So, lots of researchers had studied them at home and abroad. The present systematic study of longicorn beetles still stays on the level of morphology, and the molecular systematic in not identical. In this study the phylogeny of 6 Eodorcadion species was established based on partial nucleotide sequences (about 423bp) of the mitochondrial cytochrome b gene. The sequence characters were analyzed by phylogenetic software package to construct molecular phylogenetic trees. This study will provide basic data for further study deeply. Cytochrome b (Cytb) is one of the most widely used molecular markers in animal molecular phylogenetic studies. We used general primers CB1 and CB2 to amplify 423bp segment of Cytb gene and used it as a molecular marker to analyze phylogenetic relationship of these 6 species from Mongolia plateau. 1. The dry specimens conserved for about 40s years can be used in this study, which is beneficial to development of molecular systematics. 2. The gained sequence were processed and analyzed with Clustalx1.8, Megalign and Mega2.0 software. Through Mega2.0 software, some useful statistical data were obtained and the phylogenetic trees constructed by means of N-J, ME and MP. 3. Cytb exhibits an A/T bias across all sites (A+T=70.1%) and was most pronounced at the third position (76.4%). 4. Among the mucleotides substitution of Cytb, transition is lower than transversion. Transversion has the bias of A? T and T? A, and usually happens in the third position. Transition has the bias of A? ? G. As a typical protein-coding gene, the second position is the most stable, the first one is more variable and the third is the most variable. Although codon usage is affected by A/T bias, the amino acid composition is not varied with this bias. 5. Structure of the trees from three methods is the same. This indicates that the result is credible and Cytb is a useful marker in phylogenetic study at the generic and species level.