Population Genetics Study Of Rhododendron Subg.Rhodorastrum

Population genetic structure and genetic diversity of the current species is one of the core research contents of population genetics,which is critical for understanding the essential process of speciation.In our study,we focused on the two endemic species Rhododendron dauricum and R.mucronulatum,subordinating to Rhododendron subg.Rhodorastrum.Four single-parent inherited chloroplast gene fragments were used for genetic diversity analysis,genetic structure analysis,population demographic history analysis and divergence time analysis based on 39 populations,total 376 individusls.Finally,we simulated the distribution of R.dauricum and R.mucronulatum in the last interglacial period,the last glacial period,current period and future period using ArcGIS and MaxEnt software.The main results of this study are as follows:?1?Based on cpDNA combined data,a total of 10 cpDNA haplotypes were detected.The subgenus?H_T=0.718?and the Rh.dauricum?H_T=0.726?showed high genetic diversity.Because only one haplotype was detected in the Rh.mucronulatum,the value of H_T was 0.?2?The Nst were significantly higher than Gst in the subgenus and the Rh.dauricum,?Gst=0.821,Nst=0.957 and Gst=0.795,Nst=0.954,respectively?,indicated that they all had significant genetic structure.AMOVA analysis supported strong genetic differentiation(F_CT=0.90507)between the two subgroups of structure analysis?group A and group B?.?3?The mismatch analysis showed that Rh.dauricum individuals collected in the Greater Khingan,the Lesser Khingan and the Changbai mountain areas experienced recent population expansion events.Through Ecological Niche Modeling simulations,from the last glacial period to the present period,the Rh.mucronulatum also experienced population expansion event.?4?The divergence time of the subgenus was estimated to be about 15.76 Mya at the middle Miocene by BEAST.The haplotype divergence time of group B began in the late Miocene about 7.10 Mya,and the haplotype of group A began to differentiate at about 5.23 Mya at Early Pliocene.These two species of the subgenus,as common shrubs in temperate flora in East Asia,can undoubtedly be used as ideal materials to test the effects of climate change on the biogeographic distribution of the region.Understanding the genetic structure and population dynamic history of organisms can also provide theoretical basis and practical significance for the protection and rational utilization of biological resources.