Fine-scale spatial genetic structure within age classes of the two fragmented populations of Sinocalycanthus chinensis Cheng et SY Chang, an endangered plant species endemic to China

To support the development of conservative strategies for the protection of the endangered plant Sinocalycanthus chinensis Cheng et S.Y. Chang. We analyzed the fine-scale spatial genetic structure (SGS) of the two fragmented populations from the Dalei Mountain and Daming Mountain in China. Significantly positive SGS was observed at a distance of 20 m in the Dalei Mountain population. Significantly positive SGS was observed at a distance less than 20 m and a distance of 90 m in the Daming Mountain population. The Sp (a ratio used to compare the extent of SGS among populations) statistics were quite different between the two populations. The similar genetic patches, but different SGS patterns and intensities, might be due to the population fragmentation and subsequent change of population density and environmental factors, as well as inherent biological traits of S. chinensis. The SGS within different age classes in Daming Mountain population significantly differed from that in Dalei Mountain population, which might be due to different causes of the SGS. The main cause of SGS in Daming Mountain population might be the species traits and anthropological disturbances, while that of SGS in Dalei Mountain population might be the seed shadow overlap caused by population density and subsequent self-thinning. (C) 2012 Elsevier Ltd. All rights reserved.