Analysis of the Conservation Status, Genetic Diversity and Population Structure of Endangered Ostrya rehderiana Resources Using SSR Markers

Abstract

Climate change and anthropogenic habitat destruction have led to the extinction of many species. Ostrya rehderiana (Betulaceae) is a typical rare and endangered species, and only five wild individuals have survived. In the 1980s, the offspring of the five wild trees were planted for ex situ conservation and have grown into stable cultivated populations. To protect O. rehderiana resources, the genetic diversity and genetic structure of this species were analysed using SSR markers. A total of 167 alleles were detected among 116 individuals from the only wild population and five cultivated populations at 12 SSR loci. The genetic diversity level of O. rehderiana was He = 0.88. Genetic differentiations occurred among populations (Fst = 0.17), which was also validated via an analysis of molecular variance (AMOVA). The cultivated populations TM1, TM2 and WC showed considerable genetic differences from the wild population WP based on Bayesian clustering analysis, phylogenetic tree reconstruction and principal coordinate analysis (PCoA). The cultivated populations had more genetic diversity than the wild one. It is speculated that novel alleles may have emerged out of natural processes of evolution and adaptation. The cultivated population QY with the most unique alleles has begun to propagate seedlings naturally, and the small population size and geographical isolation may negatively influence the founding of this population. To weaken the effects of bottlenecks and genetic drift, anthropogenic gene flow among populations is necessary. In addition to the wild population, the cultivated population QY and six individuals from populations QY and WC were also found to be important for the conservation of O. rehderiana. The results of this study may guide the development of conservation policies for endangered O. rehderiana.