Grasshopper Types Of Co Ii And The 18s Rdna Gene Molecular System Studies

Acridoidea is a big superfamily in Caelifera of Orthoptera.There were about ten thousands species of Acridoidea in the worldwide,most of them distributed in tropical,temperate and the desert region.In china,there were about 8 family253 genus 1053species of Acridoidea,according to the arrangement of Zheng(2003),in recent year,several species have been published.In this paper,we are study COII and 18SrDNA gene sequence of partial species of Acridoidea and reconstruct the phylogenetie relationships.we provide molecular evidence for the phylogenetic relationships of Acridoidea.The genomic DNA were extracted from 24 species,belonging to 15 genera of 4 family of Acridoidea.We amplified the COIIgene using one pair primers,and obtained 24 sequences,the length of 684bp.We amplified the 18SrDNA gene using two pairs primers,and obtained 23 sequences,the length of 1803bp.We downloaded the COII and 18SrDNA sequence of Acheta domesticus and Ellipes minuta as outgroup.The processes of analyse contain:sequence alignment using Clustal X2.1.The base frequences, base substitutions, genetic distances and base substitution saturation analysis of DNA sequences have been analyzed by using MEGA5.Phylogentic signal have been tested via g1 and PTP tests using PAUP4.0.Based on the analyses of COII gene sequences, we reconstruct the phylogenetic relationships of these species by using PAUP4.0 and MrBayes.We can conclude the results as follows:1. The COII sequences of 24 species of Acridoidea shows a strong A+T bias:The average content of A+T in COII gene sequences is 71.2%, and G+C content is 28.9%,which is consistent with the A+T bias of mitochondrial genome of Arthropod.However,18SrDNA is well conservative, with 1774 invariable sits,30 variable sites, A+Tcontent is 47.9%, and G+C content is 52.1%,which shows a nearly equal A+Tand G+C content.2. The average transition and transversion ratio of COII gene sequence is 1.23. Transition is just a little higher than transversion. Most transition occurs between T and C. Transition in 1st and 2nd sites is higher than transversion(Rlst=3.09;R2st=2.25),Transition in 3rd sites is lower than transversion(R3st=0.80).The average transition and transversion ratio of 18SrDNA gene sequence is 1.56. Transition is higher than transversion.3. The distance of COIIgene is 0-0.132,the average is 0.081.The distance of 18SrDNA gene is 0-0.008,the average is 0.004.18SrDNA gene is rather conservative.4. g1 and PTP tests were conducted on COII gene date set,18SrDNA gene date set,and combined date set.Results show that they exist stronger phylogenetic signal. 5. Four methods are separately used to reconstruct the phylogenetic trees based on the data sets of COII gene.18SrDNA gene and combined data sets.The result from comparing these trees indicates that all the phylogenetic trees have little difference.6. Based on the phylogenetic trees,we can conclude:(1)Insect species of Arcypteridae and Gomphoceridae are clustered together in phylogenetic trees, suggesting that they have rather near phylogenetic relationships, which was consistent with the traditional classification result. Gomphocerippus rufus representing Gomphoceridae is clustered together with Arcypteridae in all phylogenetic tree.(2)The taxonomic status of Acrididae is uncertain in the phylogenetic tree.According to the topology structure of the phylogenetic trees,Acrididae clustered together with other family.Acrida cinerea belonging to Acrididae clustered together with Trilophidia annulate of Oedipodidae,and Mongolotettix japonicus of this family is clustered together with Arcypteridae. (3)Most species of are clustered together and constitute a monophyletic group.This study is using COII gene and 18SrDNA gene as molecular marker to analyze the composition and phylogenetic relationship of 4 families of Acridoidea.it provides molecular evidence for the further phylogenetic study of family level of Acridoidea and helps to refine the systematic researches.It is needed more extensive study on the phylogenetic relationships of Acridoidea.In the further study,we can increase the species and quantities of the samples,using multiple genes or whole-genome data to reconstruct the phylogenetic trees.It can gets the maximizing informations of phylogenetic.Finally accurately resolve the phylogenetic relationship of Acridoidea.