Phylogeny Of Thripini (Thysanoptera: Thripidae) Based On CO Ⅰ And 16S RRNA From China

Thripini belong to Thripinae of Thripidae in sub-order Terebrantia of Thysanoptera. Thripini is the largest group within Thripinae. This paper measured partial mitochondrial COâ… gene sequences of 18 species of Chinese thrips, and partial mitochondrial 16S rRNA gene sequences of 17 species of Chinese thrips, both of the above include 15 species of thrips within the tribe Thripidae. Data of base composition, variable sites and genetic distance have been obtained. Aeolothrips fasciatus was set as outgroup, and molecular systematic trees have been built according to MP (maximum parsimony), ML (maximum likelihood) and BI (Bayesian inference) methods. The result shows:1. The average content of T, C, A, G of COâ… gene sequences of 18 Thrips species are 36.6%, 17.0%, 32.7% and 13.7%. The A+T content is 69.3%, which is overwhelmingly larger than G+C content (31.7%). The anverage content of T, C, A, G of 16S rRNA gene sequences of 17 Thrips species are 33.7%, 17.5 %, 32.1% and 16.7 %. The A+T content is 65.8%, which is significantly larger than G+C content (34.2%). The average content of T, C, A, G of the combined sequence of 13 Thrips species are 33.7%, 17.5 %, 32.1% and 16.7% Respectively. The A+T content 65.8% is much higher than G+C content 34.2%.2. The genetic distances of 18 species of Thrips based on COâ… gene are 0.02-0.322, the average is 0.200. The genetic distances of 17 species of Thrips based on 16S rRNA gene are 0 -0.382, the average is 0.243. The genetic distances of combined gene are 0.004-0.300, the average is 0.218. There are significant linear relationship between the genetic distances and Ts (Transition) and Tv (Transversion) numbers.3. From the result of g1 tests and base substitution saturation analysis, the COâ… gene,16S rRNA gene and the combined gene show significant phylogenetic signal .4. Three phylogenetic trees (MP, ML and BI) have been built based on COâ… gene, 16S rRNA gene and the combined gene. Results have been discussed mainly based on the three trees of combined gene, which have a similar topological structure. Frankliniella, Megalurothrips and Thrips have higher evolutionary status than the rest of genus. All the three trees show that Thrips is a Paraphyletic group, and Thrips tabaci separated earlier than the rest of 2 Thrips species. Thrips flavidulus and Thrips alliorum have been grouped in the same clade. In addition, according to the MP and BI trees Taeniothrips major separated earlier than Scolothrips tatahashii. Frankliniella has been grouped in the same clade with Megalurothrips. At the base of these three different trees,Sussericothrips separated earlier than Mycterothrips, while Mycterothrips separated earlier than Parabaliothrips.The results of this study provide some new points for the Thripini classification, enrich the gene data of Thripini, and provide molecular evidences for the classification and phylogenic study of Thripini.