Molecular Phylogenetic Research Of Tenthredinidae (Hymenoptera:Tenthredinoidea) Based On Data Of COI Gene And28S RDNA

Tenthredinidae is the largest group in Symphyta:Hymenoptera with a world wide distribution. Most of the sawflies are phytophagous insects and important pests of agriculture and forest. So it is important to understand Tenthredinidae taxonomic and phylogenetic relationships for the further study such as biocontrol and so on. Currently, the abroad disputes of ordinal classification and phylogeny in Tenthredinidae have even existing in all times. There is no classification admitted by most systematists in world wide.In this dissertation, we set three species of Blasticotomidae and Xyelidae as outgroup, and reconstructed the phylogenetic relationships of partial species of Tenthredinidae based on molecular markers of COI gene,28S rDNA gene and combind database of the two genes (28S&COI) by using three methods of MP ML and BI. The resultes are showed as follows:1. The average contents of A+T to28S rDNA gene of38species in Tenthredinidae is41.8%, lower than contents of G+C. Ratio of transition to transversion (R) is1.4shows the sequence is highly conservative. The result of substitution saturation analysis and the relationship between P distance and R indicating that there are strong phylogenetic signal in the datasets of28S rDNA gene.2. The average contents of A+T to COI gene of42species in Tenthredinidae is71.0%, which shows a strong A+T bias. Ratio of transition to transversion is0.66Shows the characteristics of high mutation by the mitochondria gene. The COI gene have852base paiers and code284amino acids. The Contents of Leu are very high and the codon of UUA have the highest frequency. Because of the evolutionary pressure, every sites of the codon contained different information respectively. The second position of codons are the most conservative one with lowest substitution and parsimony informations. Substitutions of the third position of codons are highest. The relationship between P distance and R is consistent with the typical distance dependent character of mtDNA in most insects.3. The phylogenetic relationship within Tenthredinidae in this study shows as follow:11species of Tenthredininae form a monophyletic group and the relationship is:(((Macrophya+Pachyprotasis)+Tenthredo)((Tenthredopsis+Aglaostigma) Lagidina)). Allantinae is allied to Tenthredininae, but the monophyletic of Allantinae need to be studied further. Megabelesesinae differentiations earlier than Belesesinae, and they are all allied to Allantinae, this point disagree with Taeger (2010) in which Megabelesesinae and Belesesinae classified to Allantinae in broad sense. Research results also show the most basal grade of Tenthredininae is Athaliinae, not the Selandriinae by morphological study, and clearly rejected the view that belongs Athalia to Allantinae in Taeger (2010). In a broad sense Allantinae is a polyphyly group including (Allantinae+Megabelesesinae+Belesesinae+Athaliinae). In all the gene trees resolved that Selandriinae is a monophyletic group with a high bootstrap value. Dolerinae and Strongylogasterinae place the basal grade of Selandriinae, But the viewpoint of incorporate Dolerinae and Strongylogasterinae in Selandriinae in Taeger (2010) is not supported. In all the gene trees Nematinae is monophyletic in a broad sense which consists of Nematinae+Hoplocampinae (inlcuding Cladiini)+Susaninae, among this group Hoplocampinae is the top clade. In Hoplocampinae Hoplocampini and Cladiini form are polyphyly, and this incongruent with Nyman (2006).4. Among the two genes in this study,28S rDNA Plays an important role in the combined database of28S&COI. with a rapid evolution speed COI gene is limited when solving the Phylogenetic Relationships of Tenthredininae, but it is a useful marke for the phylogenetic evolution of interspecies and intragenus.