Molecular Phylogeny Of Acridoidea Based On 18S RRNA, 16S RRNA, COⅠ, COⅡ Genes

Acridoidea belongs to Caelifera, Orthoptera. At present, the system commonly used was made by Professor Yin Xiangchu and later revised by Professor Xia Kailing; and Acridoidea is divided into 8 families:Pamphagidae, Chrotogonidae, Pyrgomorphidae, Catantopidae, Oedipodidae, Arcypteridae, Gomphoceridae, Acrididae.The sequences of 18S rRNA,16S rRNA, COⅠ, COⅡgene of 10 grasshopper species were sequenced (20 sequences) or downloaded from GenBank. Nucleotides composition, substitution saturation and genetic distance were analyzed by MEGA software, and the molecular phylogenetic trees were constructed by MEGA and PHYLIP software.1. Nucleotides composition analysis:based on 18S rRNA gene sequence, average G+C content was 52.3%, average A+T content was 47.7%; based on mitochondrial 16S rRNA, COⅠ, COⅡgene sequences, average A+T content was 69.7%,65.7%,73.7%, respectively, and average G+C content was 30.4%,34.4%,26.2%, respectively; showing a strong base bias. The sequences of COⅠ, COⅡgene showed a strong amino acid bias.2. Nucleotides variation and substitution saturation analysis:based on 18S rRNA,16S rRNA, COⅠ, COⅡgene sequences, R (transition/transversion) were:1.3,0.8,0.8,0.7, respectively.3. Genetic distance analysis:based on 18S rRNA,16S rRNA, COⅠ, COⅡgene sequences, genetic distances were 0.000～0.023,0.048～0.235,0.125～0.254,0.095～0.298, respectively; comparing with outgroup Gryllotalpa orientalis, genetic distances of Acridoidea were 0.089～0.099,0.307～0.377,0.279～0.355,0.379～0.444, respectively.4. Molecular phylogenetic trees analysis:based on 18S rRNA,16S rRNA, COⅠ, COⅡgene sequences, and the sequence of constenting 4 above listed sequences, the result is as follow: firstly, outgroup Gryllotalpa orientalis was well separated from the roots of trees and 10 species of Acridoidea insects, which were well grouped together. Pyrgomorphidae had closer relationship with Chrotogonidae, together as the most ancestral group. Oedaleus asiaticus and Locusta migratoria migratoria belongs to the same family, so they have high similarity and group together. In all molecular phylogenetic trees, Pseudoptygonotus prominemarginis and Chondracris rosea rosea were not grouped together. The 8 families phylogenetic relationgships generally were:Chrotogonidae→Pyrgomorphidae→Pamphagidae→Oedipodidae→Acrididae→Gomphoceridae→Catantopidae→Arcypteridae.