Population Structure And Phylogeography Of Rhododendron Dauricum Based On Chloroplast DNA

Climatic oscillations during the Quaternary haveplayed important roles in the distributions and genetic structures of current species.Here,we investigated the population structure and phylogeography of a deciduous shrub speciesRhododendron dauricum L.based on six chloroplast regions(trnS-trnfM,trnL-ndhJ,rpoC1-rpoB,trnS-trnG,trnH-psbA,and trnK-matK).We collected a total of 166 individuals from 23 populationsacross its current distribution ranges in northeastern China,including Greater Khingan Mts.,Lesser Khingan Mts.,Changbai Mts.and Liaodong Peninsula.Based on these samples,we have sequenced the chloroplast fragments and analyzed itsgenetic diversity,genetic structure,phylogeographical structure,phylogenetic relationships,etc.Results showed that the R.dauricum used in this study harbored highgenetic diversity andChangbai Mts.and Liaodong Peninsula were identified as the geneticdiversity centers of this species.In addition,a total of 11 haplotypes were identified from theconcatenated chloroplast data set,and which showed a significant geographical distribution pattern in northeasternChina.Of these haplotypes,the individuals from Greater and Lesser Khingan Mtsclusteredas one independent clade,while the accessions from Changbai Mts.and Liaodong Peninsula fell into another clade,and the remaining clade only contained the individuals from population BY.Meanwhile,our results showed that more than 70% of the genetic variability was distributed among groups and there existed a significant phylogeographic pattern(NST>GST,P<0.01).Furthermore,results from mismatch and neutrality test failed to identify population expansion in the post-glaciations.These findings together suggested that R.dauricum shows spatial genetic structure and that the LGM has had profound impacts on the geographic distribution and genetic variability of this species.