The population genetic diversity and pattern of Pteroceltis tatarinowii, a relic tree endemic to China, inferred from SSR markers

Abstract

Pteroceltis tatarinowii (Cannabaceae), a relic tree endemic to China, is mainly distributed in limestone mountains and has a wide geographical range. In this study, 12 microsatellite primer pairs were assayed to analyse the genetic pattern and gene flow among 461 individuals sampled from 23 wild populations of P. tatarinowii. A high level of genetic diversity was detected based on high values of total alleles (159), the number of alleles (NA = 6.373), expected heterozygosity (HE = 0.696) and observed heterozygosity (HO = 0.679). The high genetic diversity in this species may be attributed to its long‐life history, wide geographical distribution and wind dispersal. Only low genetic differentiation (GST = 0.137, FST = 0.138) was found among populations. Gene flow (migrants per generation, Nm) was estimated to be 1.56. This moderate level of gene flow possibly decrease interpopulation differentiation by buffering against genetic drift and improving gene exchange. However, spatial genetic structure was detected throughou the sampled range of the species (r = 0.311, p < 0.05) as well as in southern China (r = 0.453, p < 0.05), and may be related to terrain heterogeneity and the demographic history of P. tatarinowii. The east‐west high mountains of southern China might serve as physical barriers to seed and pollen flow. The isolation and local adaptation of different refugia may further limit gene flow. In addition, geographically remote populations might fail to effectively disperse pollen and seeds. Based on the above‐mentioned results, some suggestions for the conservation of the species are presented.