Types The Chinese Tetrigoidea Part Of The 16s Rrna And 18s Rrna Gene Sequence Of Molecular Evolution And Systematics

Tetrigoidea is a small superfamily in Caelifera of Orthoptera.According to the statistic number of Yin(1996),there were about 211 genus 1062 species of Tetrigoidea,most of them distributed in tropical and subtropical areas.In China,they usually distribute in the south provinces,such as Fujian, Taiwan,Guangdong,Guangxi,Hainan and Yunnan;but in Gansu,Xinjiang and Jilin have a few species,too.Zheng(2005) discribed the insects of Tetrigoidea in the west of China about 350 species;in recent years,40-50 species have been published,so far there are about 400 species of Tetrigoidea in China.The genomic DNA were extracted from 25 species,belonging to 13 genera of 4 families of Tetrigoidea.We amplified and sequenced DNA using four pairs primers,and obtained 21 sequences of 16S rRNA,the length of 473bp;25 sequences of 18S rRNA,the length of 1752bp.We downloaded the 16S rRNA sequence of 7 species in Tetrigoidea,and 16S rRNA and 18S rRNA sequences of 4 species in Tridactyloidea as outgroups.The base frequences,base substitutions and genetic distances of DNA sequences have been analyzed by using Clustal X1.81 and MEGA3.1 softwares.Phylogentic signal have been tested via base substitution saturation analysis,g1 and PTP tests.Ressults show there are stronger phylogenetic signal in the data tests.We adopted 16S rRNA, 18S rRNA gene sequences and their conbined data set as molecular marker and reconstructed the phylogenetic relationships with NJ,MP,ML and BI methods in MEGA3.1,PAUP4.0 and MrBayes3.1.2.We can conclude the results as follows:1.The average content of A,T,G and C of 16S rRNA gene sequence of 28 species of Tetrigoidea are 29.8%,42.4%,18.3%,and 9.5%respectively,and A+T content is 72.2%,G+C content is 27.8%,which shows a strong A+T bias.The average content of A,T,G and C of 18S rRNA gene sequence of 25 species of Tetrigoidea are 23.5%,24.8%,28.3%,and 23.4%respectively, and A+T content is 48.3%,G+C content is 51.7%,which shows a nearly equal A+T and G+C content.2.The average transition and transversion ratio of 16S rRNA gene sequence is 0.6,transition is obviously less than transversion;the highest transition is in A-G,and the highest transversion is in T-A.The average transition and transversion ratio of 18S rRNA gene sequence is 1.7,transition is obviously more than transversion;the highest transition is in T-C,and the highest transversion is in T-G;Substitution saturation analysis shows the sequence is conservative.3.The distance of 16S rRNA gene is 0-0.188,the average is 0.110;The distance of 18S rRNA gene is 0-0.044,the average is 0.018;9 pare diatance is 0.000.4.The x~2,g1 and PTP tests were conducted on 16S rRNA gene data set,18S rRNA gene data set,and combined data set.Results show that they exist stronger phylogenetic signal.5.Four phylogenetic trees were reconstructed based on 16S rRNA data set of 30 species (including the outgroups),18S rRNA data set of 27 species(including the outgroups) and combined data set of 26 species(including the outgroups),all the phylogenetic trees were the similar topology structure.So we concluded that the phylogenetic relationships of the four families of Tetrigoideare that Batrachideidae is the primitive group,Scelimenidae and Metrodoridae are the middle group;and the Tetrigidae is composed of two clades,the one is original and the other is evolutionary.The other three families have a few species in this study excluding the Tetrix,so we only paid attention to the genus Tetrix.The results as follows:Coptotettix is a paraphyletic group,one evolutional clade is more related to Hedotettix and the other original clade is more related to Formosatettix;Tetrix is also a paraphyletic group,T.japonica was represented the first clade and T. dentifemura was represented the second clade,which is more related to Euparatettix.The Teredorus within Tetrigidea and Systolederus within Metrodoridae are clustered together in all phylogenetic trees,and the two genera are similar on morphological characters,thus we suggested merging the two genera to one genus of Tetrigidae.According to the phylogenetic trees and the distance between Alulatettix qinlingensis and the species within the genus Tetrix,we found the A.qinlingensis is closely related to Tetrix,and the distance between A.qinlingensis and T.japonica is smaller than the closest distance among the species of the genus Tetrix;comparing the morphological characters,we found that there are ten aspects on the sameness between A.qinlingensis and T.ruyuanensis, therefore we suggested that A.qinlingensis should be classified to the genus Tetrix.Using the mitochondrial 16S rRNA and nuclear 18S rRNA combine data in phylogenetic relationship in Tetrigoidea,this study is the first attempt.The results of this research not only provide molecular evidences for Tetrigoidea taxonomical research,but also propose new idea for the Tetrigoidea classification.It is maybe suitable to resolve accurately the relationship by extending length of sequence or adding other molecular protein-coding markers in the future.