Phylogenetic Relationship Research Of Some Species Of Pine Caterpillars Based On MtDNA-COI Gene

To investigate the phylogenetic and genetic relationships of 7 pine caterpillars, we reviewed the research methods of previous, recent progress and application of the technology. We analyzed the genetic differentiation of COI gene sequences among the species of Dendrolimus punctata punctata, D. tabulaeformis, D. spectabilis, D. superans and D. punctata wenshanensis, D. kikuchii kikuchii and D. grisea. In addition, some other genes like mitochondrial COII, ND1, Cytb, 16S and ribosomal DNA internal transcribed spacerⅠandⅡ(ITS1,ITS2) and nuclear elongation factor EF-1a were preliminary studyed, the results are showed as follows:The D. punctata punctata, D. tabulaeformis, D. spectabilis, and D. superans was analyzed based on COI gene sequences. The average base usage frequency of obtained 636bp of COI sequences is A=34.75%, T/U=34.75%, C=15.25%, G=15.25%. The D. punctata punctata has the highest genetic diversity(3.93%)and D. superans lowest(0.629%). The genetic distance from 4 spices is D. superans×D. spectabilis(0.083)>D. superans×D. punctata punctata(0.068)>D. superans×D. tabulaeformis(0.066)>D. spectabilis×D. tabulaeformis(0.057)>D. punctata punctata×D. spectabilis(0.054)>D. punctata punctata×D. tabulaeformis(0.012). D. punctata punctata and D. tabulaeformis can not be distinguished from the tree. COI is a suitable marker in Dendrolimus molecular taxonomy, and it can be applied to identify the genetic relationship from 4 kinds of pine moths.To investigate the relationships of 7 pine caterpillars based on COI gene sequences, and through alternative models and parameters selection, the best model was T92 + G (Tamura 3-parameter).Using MP and NJ methods with MEGA 5.0, the results indicate that the genetic differentiation of caterpillars were separate two branches, one is D. kikuchii and D. grisea, the rest 5 caterpillars gathered to another branch. D. punctata punctata and other three geographical subspecies come together, then come together with D. superans. With COI genetic distance we speculated that the D. punctata punctata, D. tabulaeformis, D. spectabilis and D. superans have a same ancestry; D. houi and D. kikuchii have the same ancestry, D. tabulaeformis shared the same occurring period with D. grisea; D. spectabilis ,D. superans and D. kikuchii shared the same occurring period,later than D. grisea; D. kikuchii and D. punctata punctata are not evolved from the same ancestor. Combination of genetics, chemical ecology and geostatistics results confirmed that evolution were intrinsically linked with geographical distribution.Mitochondrial gene COII as the same as COI could be used in the forphylogenetic studies;but Cytb results quite different with other genes.The ND1 sequences were too short and contained less information, so it need to be re-designed primers.To compare ITS1 and ITS2 gene sequences, ITS2 is more suitable to study the differention of inner species than ITS1. The 16S gene is not suitable for application in species level due to its higher conservative .