Molecular Evolution And Phylogenetic Analysis Of Some Species Of Oedipodidae (Orthoptera: Caelifera: Acriodidea) In China Based On Partial Sequence Of Mitochondrial 12S RRNA Gene

Oedipodidae is a large family in Acridoidea (Orthopera: Caelifera). In China, it includes 37 genera 124 species. Researches on controlling over plague of locusts were of great significance on agriculture. Molecular biological techniques were applied to insect systematics and much important progress has been made. However, studies on molecular phylogeny of Chinese Oedipodidae are rather few, and a comprehensive phylogeny is lacking. Here we report a phylogenetic analysis of Chinese band-winged grasshoppers based on DNA sequence of mitochondrial 12S rRNA gene. The goals of our study were to better resolve the phylogenetic relationships among Chinese band-winged grasshoppers and investigate the effectiveness of 12S rRNA gene sequences for reconstructing the phylogeny of Oedipodidae.Mitochondrial small subunit ribosomal RNA (12S rRNA) gene has been used for phylogenetic analyses of a wide range of species and divergence levels for their universal occurrence, sequence and structure conservation and abundance. We adopted PCR products direct sequencing technique to sequence fragments of 12S rRNA gene of 19 Oedipodidae species in China (representing 4 subfamilies and 10 of 37 genera). An outgroup, Gryllus campestris 's corresponding fragment from NCBI, and all the sequenced fragments were aligned using Clustal X and the alignment length was 546bp. All nucleotide sites were grouped to stem set and loop set according to the secondary structure model of 12S rRNA. Statistics of sequence compositions and nucleotide substitutions were obtained using MEGA2.1. PAUP*4.0blO (PPC) was used to evaluate the phylogenetic information content of the data and reconstruct NJ, MP and ML trees. Bayesian analyses were also performed with MrBayes V3.0. Sequences and phylogenetic analyses have been arrived at conclusions as follows:1. Fragments of 12S rRNA gene of 19 Oedipodidae taxa showed patterns, typical of many insects, such as high A+T content and variable distance-dependent transition/transversion (TS/TV).2. Analyses of tree length distribution and PTP test of combined data set, loop set and stem set showed strong phylogenetic signals and a strong correction of characteristics beyond that expected by random. MPT reconstructed from three data setssuggested that combined data set produced a more constructive topology while loop set and stem set separately resolved parts of the topology, which showed stem and loop of 12S rRNA gene contained different phylogenetic information and combined data was better for reconstruction. The weighted MP and unweighted MP analyses got the identical topology, which showed that stem bases' compensatory substitution didn't influence the phylogenetic analysis. Reflected from wMP analysis and corrected distance reconstruction, potential substitution saturation showed by saturation analyses also didn't matter much in reconstruction.3. Likelihood-based KH and SH tests of four topologies from MP, NJ, ML and Bayesian inference (BI) showed that although the MP tree had the lowest likelihood score, the KH and SH tests showed no significant difference in the -Ln likelihood between four trees so that MP tree was not significantly better than other trees. Therefore we can't reject NJ, ML and BI trees in favor of MP tree. Four trees were all considered good interpretations of the data provided. We concluded that the data couldn't provide enough phylogenetic information to fully resolve the relationship of the 19 species in Oedipodidae.4. The 50% consensus tree of MP, NJ, ML, BI trees showed two distinct clades: One clade includes all species of Bryodeminae and Bryodemellinae sampled, and the two Bryodemella taxa separately clustered with Angaracris and Bryodema taxa, so we considered it was appropriate to merge them as one subfamily; the other clade includes Bryodemella, Oedaleus, Gastrimarygus, Trilophidia and Aiolopus. The relationship of the species in these two clades was: (((Bryodema luctuosum luctuosum, Bryodema miramae miramae)...