Abstract: [Objective] Quercus serrata var. brevipetiolata as one of the important forest tree species in south China has degenerated due to recent human influences. Study of genetic diversity and genetic structure, as well as correlation between genetic structure and geographical distributions can help to develop sound conservation strategies for Q.serrata var. brevipetiolata.[Method] In this study, a total of 398 individuals of 24Q. serrata var. brevipetiolata natural populations across the species distribution were collected. Eight nuclear microsatellite (nSSR) markers with rich polymorphism were used to analyze the genetic diversity of each population, and genetic differentiation was estimated with analysis of molecular variance (AMOVA). Genetic structure at species level and correlation between genetic structure and geographical elements of Q. serrata var. brevipetiolata were evaluated using STRUCTURE and Alleles In Space programs.[Result] Results indicated rich genetic diversity of the species (H_e =0.43, H_o =0.28, N_a=3.67, N_e=1.96, I =0.66, PPL =82.81%). Analysis of molecular variance (AMOVA) showed that genetic variation mainly existed within populations (F_ST=0.22, P < 0.001), and the genetic diversity differed among different populations. Two groups containing the east and the west populations were plotted based on the Bayesian clustering analysis(STRUCTURE), and gene flow existed among these populations (N_m=1.88). Great genetic differentiation existed between the two groups containing the east and west geographical populations of the species (F_ST=0.25,P < 0.001), while the genetic variations was relatively low among the populations of each group. The Landscape Shape Interpolation analysis (AIS) also suggested great genetic differentiation between the east and west populations, which was consistent with the STRUCTURE cluster results. No correlation was found between the genetic distance and geographical distance (R² =0.011, P =0.07).[Conclusion] The genetic diversity analysis revealed rich genetic diversity of Q. serrata var. brevipetiolata based on the nSSR markers, which was related to its complex population dynamics, anemophilous characteristics and its habitat conditions. Great genetic differentiations exised between the east and west populations, and high differentiations were also found among the west populations. The genetic structure of Q. serrata var. brevipetiolata was probably accounted for the heterogeneity of species habitats (i.e., the western areas with more mountains; the relatively low elevations of east areas with flat terrain; the geographical isolation caused by the smooth topography in the central region) and fragmented environments caused by current human influences. Overall, our study revealed the genetic diversity and genetic structure of Q. serrata var. brevipetiolata, providing a theoretical basis for developing effective conservation strategies for this species.

Key words: Quercus serrata var. brevipetiolata, nSSR, genetic differentiation, geographical barrier, gene flow