Studies On Genetic Differentiation And Geographical Boundary Among Pinus Henryi Mast. And P. Tabuliformis Carr.(Pinaceae) Populations

Qinling-Daba Mountains geographically divide China into warm-temperate zone to the north and the subtropical zone to the south. It is also the barrier and transitional zone among many species.The landscape genetics research carried out on the Qinling-Daba Mountains can be used to explore the genetic basis of transition zone, and in the current climate fluctuations, the stability and likely changes of Qinling-Daba Mountains transition. At the same time,we are also able to reveal the possible impact of the climatic transition zone on the formation of species. In this study, we use the example of P. tabuliformis and P. henryi to elucidate the population genetic structure and geographic differentiation of the two species, to analyse the genetic relationship of two species, and to provide reference for revealing the impact of ecological transitional qualities on the species differentiation in Qinling-Daba Mountains areas.The genetic analysis of 29 populations,747 individuals was analyzed by ten microsatellite sites, and we found that the two species reveal a relatively high level of genetic diversity (He= 0.8917) in the wind-pollinated outcrossing of tree species, and show obviously distinct genetic differentiation (Fst= 0.3511) among populations. It might be attributed to complex habitat, intermittent decentralization, historical bottleneck effect, inbreeding system, and the adaptation to local environments. The genetic distance between populations was not correlated with geographic distance (r=-0.0886, p= 0.3). P. henryi mainly exists in Daba Mountains, while P. tabuliformis distributes primarily to the north of Qinling Mountains, with some remnants in Wuling and Daba Mountains. Geographical boundaries between P. henryi and P. tabuliformis mainly exist in the junctions of Qinling Mountains, Daba Mountains and Wuling Mountains.Extensive introgression exists in P. tabuliformis and P. henryi, in which several populations lied on the border have unique genetic components, probably resulted from drastically interspecific hybridization.