Molecular Evolution And Phylogenetic Analysis Of Some Species Of Catantopidae (Orthoptera: Caelifera: Acriodidea) In China Based On Partial Sequence Of Mitochondrial COⅡ Gene

Catantopidae is the largest family in Acridoidea (Orthoptera: Caelifera), and some of its species can cause serious damage in agriculture. It is important to understand their taxonomic and phylogenetic relationships. The studies on molecular systematics of Chinese Catantopidae are rather few. Specifically, more molecular markers are needed to be used for the investigation of the taxonomy and phylogenetic relationships within this family.The mitochondrial cytochrome oxidase subunit II (COII) gene sequence is the most widely used genetic marker for molecular systematics of animals, especially in insects. A total of 22 species (representing 10 subfamilies and 16 genera) and an outgroup species, Filchnerella sunanensis, were sampled in this study. The COII gene sequences were amplified using PCR, and then sequenced directly through cycling sequencing method. About 585bp fragment obtained after alignment using ClustalX1.83. Sequence statistics were performed using MEGA V2.1. Several statistical approaches were used to test the phylogenetic signal in the DNA sequence data sets. Phylogenetic analyses under the Neighbor Joining (NJ), maximum parsimony (MP) and maximum likelihood (ML) optimal criteria were performed as implemented in PAUP*4.0bl0 (PPC). Bayesian inference also employed to reconstruct the phylogeny using MrBayes V3.0. From these analyses we drew conclusions as follows:1. For the COII gene fragment of 22 species, sequences show highly A+T bias, with average of 69.2%, and the 3rd codon positions have the highest A+T bias (88.8%). The transition/transversion (TS/TV) ratios are dependent with genetic distances. Amino acid sequences are composed of 19 amino acids, lack of Cys. The most common amino acids are Ile, Leu, Ser, Thr, and Asp.2. Several methods , including substitution saturation analysis, tree length distribution analysis, and PTP test, were adopted to measure the phylogenetic signal of combined data set and three partition data sets, which were defined basing on different codon positions. The results showed that all of the different data sets contain strong...