Molecular Evolution And Phylogeny Of Some Species Of Oedipodidae Based On Cyt B Gene Sequence

Cytochrome b (Cyt b) is one of the most widely used molecular markers in animal molecular phylogenetic studies. We designed one primer pairs CTB-1, CTB-2 to amplify about 580bp of Cyt b gene sequence as a molecular marker to analyze phylogenetic relationship of 14 species of Oedipodidae in China. DNA sequences were aligned using CLUSTAL X, followed by refinement by eye based on the corresponding deduced amino acid sequences. After cutting off 5' and 3' termini unaligned sequences, we get 462 bp segment. Aligned sequences were imported into MEGA2 and PAUP*4.0 for phylogenetic analysis using MP, ML,ME and NJ method. In each tree-building method, several distance measures or algorithms were used, but all these distance measures or algorithms produced essentially the same results as follows:1. Cyt b exhibits an A/T bias across all sites (A+T =71.3%), which was most pronounced in third position (86.5%) . A/T bias appears consistent in intrageneric species.2. Among the nucleotides substitution of Cytb, transition is obviously higher than transversion. Transversion has the bias of A→T and T→A, and always happen in the 3rd position. The high content of A+T in the 3rd position is correlated with the variance of amion acid. As a typical protein-coding gene, the second positions were least variable, first positions were more variable,and third positions were the most variable. Although codon usage is effected by A/T bias, the amino acid composition is not varied with this bias.3. The result supports Oedipodidae as a family. The result of molecular evolution and systematic study of Cytb indicates it is appropriate to consider Oedaleus manjius and Oedaleus infernalis as two separate species. The result also shows that Bryodemellinae and Bryodeminae should be united as one subfamily.4. The Oedipodidae family can be divided to four subfamilies. A(Aiolopus Fieber), B(Sphingonotus Fieber), C((Locusta L.+ Gastrimargus Saussure) + Oedaleus Fieber), D((Bryodemella Yin + Bryodema Fieber) + Angaracris B.-Bienko). The phylogenetic relationship of these four subfamilies is(((B+D)+C)+A).5. The interspecific and generic relationship within subfamily Bryodeminae and Bryodemellinae is uncertain. Additional sequences and species need to be sampled in order to resolve this ambiguity.6. We examined the mode and tempo of evolution of Cyt b in Oedipodidae. For these grasshoppers, the most common amino acids and codons are Leucine(TTA), isoleucine(ATT) and phenylalanine(TTT). Sequence divergences within these grasshoppers indicate that Cyt b is a useful marker at the generic and species level for phylogenetic study, but there is problem at the subfamily level.The present study provided some molecular data for the phylogeny of intersp-ecies and intergenus of partial species of Oedipodidae in China.