Study On Phylogeography And Landscape Genetics Of Cornus Kousa Subsp.Chinensis

Cornus kousa subsp.chinensis belongs to the genus Cornus,which is endemic to East asia.The molecular study of C.kousa subsp.chinensis can provide a excellent model system for speciation,hybridization and introgression.In this study,the genetic structure,genetic diversity and glacier refuge of 19populations were analyzed of intergenic spacer.The main contents and results are as follows:1.The study of phylogeographicTwo pairs of primers trn L-trn F and rpl14-rpl36 with single band and high polymorphism were selected to screen the primers of cpDNA spacer,and 135individuals of 19 populations were sequenced.Where in the sequence length of rpl14-rpl36 is 605bp and the sequence length of trnL-trnF is 961bp.Adding the lamp tree for the outer group,a total of 10 haplotypes.Our results indicated that the genetic diversity of C.kousa subsp.chinensis was not high,the haplotype diversity?H_d?was0.689,and the nucleotide diversity???was 0.002.IBD analysis suggested that the genetic differentiation was caused by geographical distance.In this study,153 alleles were obtained by SSR analysis with 8 pairs of primers.The average observed heterozygosity?H_o?was 0.674,the average expected heterozygosity?H_e?was 0.578.N_m was 1.099,F_st=0.185.The structure analysis showed that the C.kousa subsp.chinensis were from two gene banks,and the bottleneck effect showed that poputations of the C.kousa subsp.chinensis had not recently undergone bottlenecks.The inbreeding coefficient analysis?F?analysis showed that the C.kousa subsp.chinensis were heterozygous.Hardy-Weinberg test found that the C.kousa subsp.chinensis deviated from the balance,which might cause by possible heterozygous excess.There were no obvious geographic Structures among populations and molecular variance?AMOVA?showed that the variation of the population was mainly in the group?73.04%?.From the PCoA analysis of the C.kousa subsp.chinensis,the composition of Anfu and other groups were inconsistent.UPGMA cluster analysis also obtained the same result.2.The study of landscape geneticsBy collecting the distribution points of C.kousa subsp.chinensis,simulating the potential distribution area and connectivity in different periods,the effects of 20environmental factors on the potential distribution of C.kousa subsp.chinensis were explored.The results showed that the main factors affecting the distribution of precipitation were the coefficient of variation of precipitation,the lowest temperature of coldest month,the average temperature of cold season and the seasonal variation of temperature.The potential distribution of the C.kousa subsp.chinensis shows that the last glacial period to the present distribution area has been significantly reduced,and now there is no significant change to 2080.The study of the connectivity of the C.kousa subsp.chinensis shows that the genetic exchange of the C.kousa subsp.chinensis had changed expand at the junction of Hubei and Jiangxi and Anhui at the last glacial period,and there is no significant change to 2080.3.Inference of glacial refugiaThe TCS network based on cpDNA haplotype data shows that Hap1 and Hap2are widely distributed haplotypes,and there are 4 haplotypes in Xuanen,and Wudang Mountains in Hubei with private haplotypes.Combined with the distribution of C.kousa subsp.chinensis to simulate the speculation of the C.kousa subsp.chinensis of the glacial refugia is Wudang Mountain and Xuanen,Wudang Mountain and Xuanen is the origin of the C.kousa subsp.chinensis.