Phylogeographic investigation of Elaeagnus mollis revealed potential glacial refugia and allopatric divergence in central China

Climate and geography oscillations in the Quaternary profoundly influenced the distribution pattern and genetic structure of plant species. Phylogeographic investigations have been numerously conducted in biodiversity hotspot regions. However, other regions have received less attention and these places may serve as potential glacial refugia for plant species. In the study presented here, phylogeographic pattern of Elaeagnus mollis , a plant species exclusively distributed in central China, was investigated using multiple nSSR loci and chloroplast fragments. As an endangered species in China, the genetic diversity of E. mollis was relatively high ( N a = 7.82, H O = 0.532, and H E = 0.623). Genetic differentiation ( F ST ) between the two main distribution regions, Shanxi and Shaanxi provinces, was 0.23177. STRUCTURE analysis of nSSR data as well as phylogenetic construction of chloroplast haplotypes clearly distinguished two distantly sublineages, corresponding well with two distribution regions. Multiple factors such as outcrossing were thought to contribute to the high level of genetic diversity. The topographically heterogeneous regions and the low dispersal ability of seed and pollen may lead to high genetic differentiation between these two regions. Two potential glacial refugia for E. mollis located in adjacent regions to the Qinling Mountains and south of the Loess Plateau were revealed, and allopatric divergence in separated glacial refugia may directly lead to the present phylogeographic pattern of this species. This study set a solid foundation for future protection and sustainable utilization of this important germplasm resource.