Genetic diversity of Rhododendron simsii Planch. natural populations at different altitudes in Wujiashan Mountain (central China)

摘要

Altitude could greatly influence species distribution and even their genetic diversity. However, it is unclear how altitude has affected the genetic diversity and population structure of Rhododendron simsii Planch., an dominant forestry species in north temperate forest. In this research, 22 polymorphic EST-SSR markers were utilized to assess the genetic diversity of R. simsii population distributed at different altitudes of Wujiashan Mountain, a major peak of Dabie Mountains (central China). Totally, 203 alleles were obtained, and each locus gave out 5 to 19 alleles. High genetic diversity existed, as Nei's gene diversity (h) and Shannons Information index (I) ranged from 0.728 to 0.920 and 1.430 to 2.690, with the mean value of 0.821 and 1.916,respectively. In particular, 11.1% of genetic differentiation was maintained between populations, while 88.9% occurred within populations. Moreover, moderate gene flow (2.001) among populations was observed, which could effectively resist genetic drift. The genetic diversity of all these five R. simsii populations varied significantly with elevation, basically showing high-low-high pattern with elevation increase. Without human intervention, genetic diversity of R. simsii populations might increase with the altitude. At the significance level (p < 0.05),negative correlation was found between genetic diversity and attenuation rate of light intensity (r=-0.873). Soil of Wujiashan Mountain was acid (the pH value ranged from 4.33 to 4.70), which was rich in organic matter, available phosphorus, available potassium, and alkali hydrolysable nitrogen, as these soil factors interacted with each other to affect the growth of R. simsii population. This research would contribute a lot to the knowledge of evolutionary history of R. simsii species and benefit subsequent management and conservation actions.