Analysis Of Genetic Variability In Natural Populations Of Calycanthus Chinensis With RAPD Markers

Calycanthus chinensis Cheng et. S. Y. Chang is a rare and endemic species in china. 60 individuals from three natural populations are randomly amplified with 22 arbitrary primers and generates 238 bands, ranging in size from 300 bp to 2.5 kb. Based on these, genetic polymorphism, structure and divergence are analyzed, and the following conclusion are thus obtained.1. At the species' level,the percentage of polymorphic loci (P0.05) and gene heterozygosity(He) of Calycanthus chinensis are 44.1% and 0.229 respectively,which indicate a lower level of genetic diversity in natural populations of Calycanthus chinensis.2. At the populations' level ,the average percentage of polymorphic loci (P0.05) and gene heterozygosity(He) of three populations are 32.8% and 0.164 respectively , in which population of DaMing Mountain is the largest (P0.05=37.0%;He=0.201) , the second is the population of Shun Xi (P0.05=31.5%;He=0.148) , the lowest is the population of Tian Tai (Po.o5=29.8%;He=0.144). These indicate that the genetic polymorphism within the population of Da-Ming Mountain is the Highest ,the population of Tian Tai is the lowest in three natural populations.3. The value of Gst suggests that there are 71.6% genetic variation within populations and 28.4% genetic variation among populations which indicates the evident divergence among populations.4. Genetic distance between populations of Da-Ming Mountain and Shun Xi is the lowest, the largest is between populations of Da-MingMountain and TianTai, which are related to geographic distance.5. Gene flow (Nm) is 0.631<1,which indicates the difficult in genetic exchanging among populations.According to these results and other concerned biology research, the causes of Calycanthus chinensis endangered are analyzed and the correspond conservation strategies are proposed.Meantime, the relationship among Calycanthus chinensis, Calycanthus floridus and Calycanthus occidentalis are analyzed. It shows that Calycanthus chinensis is far from the other two species and more similarity to Calycanthus floridus relativity. Combining with research before, the probable origin of these three species is also analyzed.