| 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 Catantopidae 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 subunitⅠ(COⅠ) and cytochrome oxidase subunitⅡ(COⅡ)gene sequences are the most widely used genetic markers for molecular systematics of animals,especially in insects.A total of 15 species(representing 3 subfamilies and 9 genera) and an outgroupspecies were sampled in this study.The COⅠand COⅡgene sequences were amplified using PCR,and then sequenced directly through cycling sequencing method.About 633bp of COⅠ(complete sequence of COⅠabout 1.5kb ) and 684bp complete of COⅡobtained after alignment using ClustalX1.83 Sequence statistics were performed using MEGA V4.0 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~*4.0b10(PPC).Bayesianin ference were also employed to reconstruct the phylogeny using MrBayes V3.1.2 from these analyses,we drew conclusions as follows:1.For the complete COⅡgene sequence of 14 species,sequences show highly A+T bias,with average of 70.4%,and the 3rd codon positions have the highest A+T bias(87.7%).The transition/transversion(TS/TV) ratios are dependent with genetic distances.Amino acid sequences are composed of 20 amino acids;the most common amino acids are Ile,Leu,Ser,Thr,and Asp.For the COⅠgene fragment of 11 species,sequences also show highly A+T bias,with average of 65.4%, and the 3rd codon positions have the highest A+T bias(87.0%) as well.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 Phylogenetic signal.3.Phylogenetic relationships of 15 species were inferred through NJ,MP,ML and BI methods. Topologies of four trees are not compatible with each other in some of nodes,hence proving that the two data of COⅠand COⅡmay have limited phylogenetic information to fully resolve the higher level of their relationships of these species.4.COⅡgene has been proven useful to infer phylogenetic relationships among species and genera within subfamily,but its ability to resolve phylogenetic relationship among subfamilies seems limited.By sequencing,studying the molecular evolution and phylogenetic relationships of the complete COⅡgene sequences of 14 Chinese grasshopper's species of Catantopediae,we provide molecular evidence for the phylogenetic relationships.We hope this study can refine the taxonomy and stimulate further study on Catantopediae insects.5.Using the fragment of mitochondrial gene COⅠ,we present a phylogenetic analysis based on 11 species drawn form 9 genera and 3 subfamilies,the relationships among genera and subfamilies are,however,less well defined.The reasons may be as follows 1) the COⅠbarcode used in this study is short,2) the species in the study is limited.In summary,COⅠgene proved a useful marker to analyse the phylogenetic relationships within genera.6.The phylogeny of 3 subfamilies and 5 genera are as follows:(1).Coptacridinae is not monophyly;(2).Eyprepocnemidinae and Catantopinae are close relationship than Coptacridinae; (3).Traulia and catantops grouped together and showed close relationship;(4).The moleculer phylongeny of Apalacris eminifronta is identical to prevoous morphological phylogeny;(5). Ecphanthacrismirabilis and Apalacris appeared close relationship. |
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