Abstract:

Sinomanglietia glauca, a species endemic to Yichun in Jiangxi Province and Yongshun of Hunan Province in Central China, was listed as Category I of the National Key Protected Wild Plants in 1999 (as a synonym of Manglietia decidua). Several studies on the population genetics of this endangered species have been reported. However, these studies either excluded Hunan populations or failed to detect any variation within populations. In this study, all four known populations of S. glauca found were used to investigate genetic diversity and genetic structure using nuclear microsatellite markers. Our results showed that S. glauca had relatively low genetic diversity (A = 2.604, H_E = 0.423) and significant population differentiation (F_ST = 0.425). Assignments analysis by STRUCTURE and Principal Coordinated Analysis indicated that Jiangxi and Hunan populations formed two independent groups. Only one natural breeding population was identified in Jiangxi whereas two were revealed in Hunan. We found a striking heterozygosity excess in the Hunan populations, a phenomenon that might be caused by allelic frequencies differing between male and female parents by chance alone within small population. The results of this study suggest that S. glauca could have experienced recent historic bottleneck(s) which resulted in reduction of population size, loss of genetic diversity and strong population differentiation. The distribution pattern of genetic diversity clearly indicates that S. glauca should be treated as three conservation units, i.e., two evolutionarily units (Jiangxi unit and Hunan unit), and Hunan ESU subdivided into two management units (YPC and LJC).

Key words: Sinomanglietia glauca, microsatellite, genetic diversity, genetic structure, conservation unit