SEMINARIO: Species divergence and population evolutionary history of Chinese endemic genus Dipteronia
Dipteronia Oliv. is a relict genus endemic to China, comprising two extant species, Dipteronia sinensis Oliv. and D. dyeriana Henry. Dipteronia sinensis has a relatively extensive range in central and SE China, with most populations distributed as isolated stands at altitudes of 1000–2500 m in a mountain riparian warm-temperate deciduous forest. In contrast, although D. dyeriana is also inhabiting mountain riparian forests, current populations are restricted to a small area in SE Yunnan Province. Currently, D. dyeriana is listed as ‘Endangered’ (EN) according to the latest version of the IUCN red list both at national and global level, as well as in the Red List of Maples. According to the latter list Dipteronia sinensis is classified as ‘Near Threatened’ (NT), albeit these authors warn that it might become “Vulnerable” (VU) because of deforestation and poor regeneration. Historical geological and climate events are the most important drivers of interspecific/intraspecific divergence in plants. However, the species divergence and populations evolutionary history of extant relict flora in East Asia remain largely unknown. We used molecular data (chloroplast DNA, nuclear gene regions and nuclear microsatellite loci) for 45 populations (789 individuals) of these two species to examine how their populations have evolved. Besides, niche comparison (E-space and G-space) and least cost path (LCP) approach were used as a complementary tool to the genetic markers in order to reconstruct past species distributions and population connectivity. Our findings provide compelling evidence that both topography and climate have shaped the pattern of genetic variation of Dipteronia species.