Genetic Diversity Of Taxus Chinensis Var. Mairei In Fragmented Habitat

Taxus chinensis var. mairei is an edemic species in China, its populations declined rapidly tothe edge of extinction because of the habitat loss and fragmentation. It s listed as key protectedplant in Class I by Chinese government. Research on conservation strategies of the plantpopulation was in progress, and conservation genetics was also carried out step by step.Microsatellite markers were used for conservation genetics study. Polymorphism microsatelliteloci were suitable for research on heterozygosity, history and heterogeneity of populations.The marker was also used to identify the barrier for gene flow between fragmented populations.We planed to isolate some polymorphism microsatellite loci using enriched library method forthe study on gene flow and spatial genetic structure of the plants. Now, The populations ofTaxus chinensis var. mairei fragmented seriously, even dotted distribution. The species distributedin limited range as small population status. Habitat and fragmentation influenced seriously on thedistribution and diversity of species. It s also regarded as major threaten to the component,construction and function of biodiversity. Not only component, size and process of eco-system,but also genetic structure the fragmentation influence on. Isolation of fragmentation hindered thegene flow between habitat patches and lead to excess inbreeding. Gradually, Allele was lost andgenetic diversity declined. We were interested in the fragmented populations of Taxus chinensisvar. mairei and wanted to know the genetic diversity, gene flow and genetic difference of them.We also wanted to know how the gene flew between the fragmented populations since they werefragmented seriously. Landscape genetics method were used to study whether the ridge ofmountain hinder the gene flow of Taxus chinensis var. mairei. The result conveyed as follows:1. Isolated11polymorphism microsatellite loci from Taxus chinensis var. mairei. Testing the11loci with32samples, we found77allele. There were most allele in Locus Tach9(10allele) andfewest in Locus Tach1(5allele). Mean of allele in all loci is to5. Expected heterozygosity is0.5196to0.8680with a mean of0.7548; Observed heterozygosity is0.2500to0.8333with amean of0.6186The PIC value is0.4891to0.8432with a mean of0.6233.2. Study on the genetic diversity of Taxus chinensis var. mairei in fragmented population. Theresult indicated that number of allele and richness of allele sustain in high level. Heterozygositydeficiency was not significant in the population researched. AMOVA analysis showed thatgenetic variation existed within population, which inferred that genetic differention amongpopulations was not to significant level especially. Meanwhile, Genetic differention amongpopulations has being found to a certain extent. Fixation index Fstamong population is most upto0.4301, Fstin all populations is0.14. Nmvalue between populations which is not up to1hold34.8%. Considering on the fragmentation status of Taxus chinensis var. mairei, We believed that genetic differention among the populations had increased, and the gene flow between somepopulations had been hindered.3. Study on the barrier for gene flow by moutain ridge in mountain landscape. Assignment testwas taken by Monmonier s maximum difference algorithm, SAMOVA, and two bayesianmethods STRUCTURE and TESS to analysis the landscape genetics structure and identify geneflow barrier for Taxus chinensis var. mairei. Through analysis, we found populations at both sideof the mountain ridge(700m) existed genetic differention which is larger than other pairpopulations of Taxus chinensis var. mairei, which indicated the ridge of mountain(700m)related to the genetic differention and hinder the gene flow.