关键词: 光皮桦, 海拔, 遗传多样性, RAPD, 生态因子

Abstract: The random amplified polymorphic DNA (RAPD) technique was used to evaluate the genetic diversity and population structure of 91 genets from four natural populations of Betula luminifera at different altitudes in Wuyi Mountains, Fujian Province, east of China. Eighteen random primers (out of 139 employed primers) produced a total of 199 scorable amplified fragments, of which 174 (87.44%) were polymorphic across all individuals. The genetic diversity of B. luminifera at the population level and species level was PPL=60.05%,h=0.224 2, I=0.318 1 and PPL=87.44%, h=0.344 2, I=0.489 9, respectively. The level of genetic variation varied regularly with different altitudes, that is, the level of genetic variation of the population was the highest at the altitude of 580 m (Pop1), and it became dropping for the populations at the altitude of 750 m (Pop2), 980 m (Pop3) and 1 250 m (Pop4). The high value of differentiation (G_st =0.348 6) and analysis of molecular variance (AMOVA) indicated there was significant genetic differentiation among populations, and about one-third of the variations occurred among populations. Pearson correlation analysis further revealed that the genetic diversity within populations was significantly correlated with the altitude and climatic factors (annual average temperature and annual precipitation), and soil nutrient factors (total nitrogen, C/N ratio and organic matter). Mantel tests showed that there was significant correlation between the genetic distances among populations and the distance of elevation, and the divergence of soil nutrient factors. The results of the present study suggested that the genetic differentiation among populations of B. luminifera at different altitudes may be caused by the ecological factors of different altitudes and gene flow.

Key words: Betula luminifera, altitude, genetic diversity, RAPD, ecological factors