Fine Scale Genetic Structures And Gene Flow Of Camellia Chekiangoleosa Of Laohunao Nature Reserve In Jiangxi Province

Camellia chekiangoleosa Hu,one of the species of Camellia in Theaceae,is a key protected plant in Jiangxi Province.A large wild population of C.chekiangoleosa has been found Laohunao Provincial Nature Reserve and its adjacent areas in Le’an County,Jiangxi Province.However,its habitat was severely destroyed by human activities and excessive utilizations.By studying the genetic structure of C.chekiangoleosa,its potential for survival,adaptation,and development in the environment can be evaluated.This can more effectively propose targeted protection strategies.Therefore,this study carried out an investigation into the status quo of C.chekiangoleosa in the area,and explored the population genetic structure and genetic diversity among different subpopulations to formulate scientific conservation strategies.Through field investigation,population sampling and Genotyping-by-sequencing,the distribution area and genetic diversity of C.chekiangoleosa were preliminarily estimated in the study.The main results are as follows:（1）The study area is rich in C.chekiangoleosa,but the area is undergoing wind power development.The C.chekiangoleosa population is mainly threatened by habitat destruction,broken branches for fruit picking and excavation.（2）The investigation of the communities structure of wild forest in C.chekiangolosa showed that there are 66 species of plants belonging to 50 genera in 31 families,in 5community plots.In all the sample plots,species of the tree layer is the most abundant,with a total of 32 species belonging to 24 genera in 15 families.It is preliminarily estimated that the distribution area of the wild community of C.chekiangolosa in the study area is 54729 m²,with a total of 14545 plants.（3）119 individual leaves from 9 subpopulations have been used as DNA materials,and 13463 high-quality SNP loci have been obtained using Genotyping-by-sequencing（GBS）.The analysis showed that the level of genetic diversity of C.chekiangolosa is high in the study area.The Shannon index（I）was0.433;The observed heterozygosity（Ho）was 0.412;The expected heterozygosity（He）was 0.285;The percentage of polymorphic loci（%P）was an average of89.08%.（4）According to the results of AMOVA,genetic differentiation mainly exists within the population with 93%genetic variation,and F_ST is 0.065.The population has already experienced moderate genetic differentiation,with N_m of 3.596.Based on STRUCTURE analysis and PCA analysis,9 subpopulations may be derived from 4different gene pools.（5）According to the results of MEMGENE,ridges and valleys have an effect on population genetic differentiation and gene flow.The results of MMRR and Mantel tests showed there was a significant correlation between geographic distance and genetic distance.It is suggested that terrain and geographical distance may be the factors influencing genetic differentiation and gene flow among populations of C.chekiangolosa.In summary,there is a moderate degree of genetic differentiation in the wild population of C.chekiangolosa in the study area,with genetic variation mainly within the population,which may be related to severe habitat fragmentation and geographical barriers among subpopulations.This study shows that geographical distance,ridges,and valleys can affect genetic differentiation.This will limit gene flow among subpopulations.Smaller subpopulations may lose genetic diversity due to factors such as inbreeding and genetic drift,leading to their ability declined that adapted to environmental changes and evolutionary ability,ultimately leading to population decline.Therefore,it is necessary to combine in situ conservation,habitats restoration,publicity and population monitoring in order to maintain the population size and genetic diversity of C.chekiangolosa.