Combining restricted gene flow, local microhabitat, and habitat fragmentation shapes the fine-scale spatial genetic structure of Fagus hayatae Palib. ex Hayata in Micang Mountain

The beech species Fagus hayatae Palib. ex Hayata is an important relict tree species in subtropical China, which accumulated a wealth of genetic variation during evolution. To revealing its regeneration dynamics, we analyzed the spatial genetic structure and gene flow of Fagus hayatae natural population in Micang Mountain (MCM), China, by using 10 pairs of microsatellite primers. The genetic diversity of F. hayatae MCM population was at the low level among tall trees. The results of Fij and Sp analysis showed that the SGS strength of F. hayatae in MCM were 40 m, the strength of SGS was stronger in saplings compared to adult and old trees. The mean dispersal distance of pollen and seeds were 83.04 m and 30.14 m, respectively. In fine-scale space, F. hayatae population in MCM is poor in genetic variation due to the restricted gene flow and significant SGS, and the strength of SGS and the dispersal distance of gene flow of F. hayatae are influenced by the limited seed dispersal, habitat fragmentation, and microhabitats. During ex situ protection of F. hayatae , the sampling distance between individuals should be greater than 40 m to ensure the most complete genetic efficiency.