Study On The Sampling Strategy Of Endangered Plants

In this thesis, the sampling strategy of the endangered plant was studied. These kinds of sampling methods were usually used in the core collection construction. To make this study more objective, the number of polymorphic loci (A), the percentage of polymorphic loci (p), Hs, Hi, Gst, and the number of the captured genes were taken as the main indices of genetic diversity. And the efficiency of two sampling methods (one is random sampling and the other is stepwise clustering method) was compared in capturing genetic diversity at different sampling proportion based on the RAPD, ISSR and the allozyme data of Changium smyrnioides, Dysosma versipellis, Ginkgo biloba and Calycanthus chinensis. In addition 1000 samples were created by using Monte Carlo method with respective sampling proportions (based on the empirical data from 3 endangered plants: Changium smyrnioides, Dysosma versipellis, Calycanthus chinensis). Based on the gene capture curves and gene increasing curves and the comparison of them , the best sampling proportion of the three plants were determined. The results are as follows:1. A software PGDC 1.0 for the core collection construction and the protection of endangered species was designed and developed. Compared with the PopGenl.32, this software has several advantages, for example, more genetic diversity indices; two kinds of sampling unit (one is population and another is individual) and 15 genetic distance offered to select for scientists are included and huge data can be dealt with by it. In conclusion, the PGDC 1.0 is a useful and practical software in conservation genetics.2. By comparing the random sampling method and stepwise clustering method through PGDC 1.0, it can be found that the stepwise clustering method is more efficient and more stable than random sampling method in the aspect of conservation genetics; generally the 95% alleles of initial collection could be captured at 15% sampling proportion.3. We used the Monte Carlo method with respective sampling proportions to create 1000 samples (based on the empirical data from 3 endangered plants:Changium smyrnioides, Dysosma versipellis, Calycanthus chinensis). Based on the comparison of the gene capture curves and gene increasing curves, the best sampling proportion of these three plants can be determined (all were 25%). However, it does not mean that the best sampling proportions of all other species are 25%. By 25% sampling proportion, the indices of these 3 plants are: the number of polymorphic loci was 163, 12, 10,;the percentage of polymorphic loci was 40.85%, 32.43%, 25% and the heterozygosity was 0.2744; 0.1943, 0.0638 respectively. All of the genetic indices were similar to those of the samples that contain the 95% genetic information of the whole population. So it is believable to determine the best sampling proportion by using Monte Carlo method and gene curves analysis.