Molecular Phylogeography Of Caragana Microphylla Lam. Inferred From Chloroplast DNA Sequences Variation

In order to explore the phylogenetic geography model on Caragana microphylla Lam. in China eight populations of Caragana microphylla Lam., including 157 individuals, in Inner Mongolia were taken as experimental samples and chloroplast trnL-trn F and psbA-trnH sequence variation(non-coding spacer) were examined. By analyzing chloroplast DNA(cpDNA) sequence variation, haplotypes and calculated the genetic diversity indexes were obtained, including haplotype diversity, Hd, and nucleotide diversity, Pi. Analysing the population structure of Caragana microphylla, we built the N-J clustering figure. Haplotype network within the populations was constructed based on maximum parsimony standard while we conferred the phylogenetic relationship among haplotypes. The main results are as follows:(1) The sequencing results on cpDNA non-coding region sequences(trnL-trnF and psbA-trnH) were analysed and found that the sequence length totally is 1244-1250 bp. The sequences were aligned with 3 polymorphic sites and five cpDNA haplotypes were identified(H1, H2, H3, H4 and H5). There were 75 individuals containing H3 while there were 6 individuals containing H2. Total haplotype diversity, Hd, was 0.626, and nucleotide diversity, Pi, was 0.00091.(2) The genetic diversity index, Fst=0.38755(P=0.0000), were obtained by the population genetic differentiation coefficient analysis, which showed that 38.755% of variance is among populations and 61.245% of variance is within populations, so variation comes mainly from within populations rather than among populations, but differentiation has been detected among populations in a certain degree.(3) The neighbor-joining tree showed that five cpDNA haplotypes were structured into two monophyletic groups. The one monophyletic group included the populations distributed in the city of Siziwang banner, Huade County, Chahar banner, Zhengxiangbai banner, Duolun County, Xianghuang Banner, while the other one included the populations distributed in Xinbarhu left banner and Dongwu banner population. The population from Xinbarhu left banner in Hulun Buir city had haplotypes which are different completely from the population in Huade County, therefore, they have the farthest genetic relationship.(4) The first step in the evolution route cotains the populations came from Dongwu banner in Xilinguole Meng and Xinbarhu left banner in Hulun Buir city(including H4, H5); the second step cotains the populations came from Duolun County(including H3, H4, H5) and Zhengxiangbai banner(including H2, H3, H4) in Xilinguole Meng; the third step cotains the population came from Siziwangqi(containing H1, H2, H3)in Wulanchabu city; the forth step cotains the populations came from Huade County, Chahar banner in Wulanchabu City and Xianghuang Banner in Xilinguole Meng City(including H1 and H3).