Microsatellite Analysis Reveals Interpopulation Differentiation and Gene Flow in the Endangered Tree Changiostyrax Dolichocarpa (Styracaceae) with Fragmented Distribution in Central China

Polymorphic simple sequence repeat (SSR) markers were used to investigate the impact of habitat fragmentation on the population structure and gene flow of Changiostyrax dolichocarpa, a critically endangered tree in central China. Intrapopulation genetic diversity, population structure and gene flow in the five extant populations of this species were analysed by eight SSR markers. Intrapopulation genetic diversity results suggest that C. dolichocarpa remnants maintained a relatively high degree of genetic diversity despite severe fragmentation. Low genetic differentiation among populations was found based on Wright's F(ST) and amova analysis. Both the F(ST)-based estimate and private allele method revealed high historical gene flow among the remnant populations. Recent immigrants, detected by assignment tests, tend to decrease from the grandparent generation to the current generation. The potentially highly restricted current gene flow among fragments may render the fragmented populations of C. dolichocarpa at a higher risk of local extinction several generations after fragmentation. Both in situ and ex situ conservation management for the remnant populations of C. dolichocarpa are therefore urgently needed to rescue remaining genetic diversity.