The Genetic Diversity Of Dendrolimus Tabulaeformis In Forests Of Different Stand Types

This study, by use of AFLP technique, examined the genetic structure and diversity among the 3 natural populations of the Chinese pine caterpillar(Dendrolimus tabulaeformis Tsai et Liu) in 1 Pinus tabulaeformis- Dahurian larch mixed forest and 2 Pinus tabulaeformis pure forests from Pingquan county. Base on the amplification bands,using POPGENE software, genetic diversity were analyzed. Besides, investigations on plant species diversity,forest crown density,incidence extent,gradient and exposure of 3 forest communities were taken,while dilution heat method and semi-micro Macro Kjeldahl method were used to determine the content of organic matter and nitrogen in soil.According to investigation results, DPS V7.05 software were applied to calculate Shannon-weaver index of diversity and Simpson's diversity index.Finally,used principle component analysis to evaluated the effect of environmental conditions on the genetic diversity of D.tabulaeformis populations.This test has developed a set of optimized response system of amplified fragment length polymorphism,which provides a powerful tool for investigation of genetic variation of 3 natural populations.5 primer combinations with good repeatability,stability and polymorphism were screened from 50 AFLP primer combinations of pine caterpillar relative species to amplified by PCR on 135 DNA samples of 3 D.tabulaeformis populations. 146 resoluble DNA bands were gained which include 124 polymorphism sites.The research result shows the genetic diversity of D.tabulaeformis is very abundant ,but there is relatively low inter-population genetic differentiation while most resided within the different populations.The effect of stand type on the genetic diversity of D.tabulaeformis populations is marked. Nei's gene diversity and Shannon's information index of populations in pure forests were both higher than populations in mixed forest,which means genetic diversity of populations in pour forests were more abundant than population in mixed forest.The result of principle component analysis shows that the growth status is main factor which influence genetic diversity of D.tabulaeformis populations.Besides, site conditions had some effects on it.A integrated effect was produced by all site conditions,so main factor could not be judged.Mixed forest has a great influence on gene flow among different D. tabulaeformis populations,because gene flow between population in mixed forest and in pour forests was lower than gene flow between 2 pour forests.D.tabulaeformis gene flow between population in pour forest with larger species abundance and in mixed forest was lower than between population in pour forest with lower species abundance and in mixed forest,which showed that the correlation between gene flow among different populations and species abundance of pine forests is negative.