Format: ORAL

Yi-Gang Song1, Tian-Rui Wang1, Zi-Jia Lu1, Hong-Hu Meng2, Si-Si Zheng1, Gregor Kozlowski1,3,4

1 Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, China 2 Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, China 3 Department of Biology and Botanic Garden, University of Fribourg, Fribourg, Switzerland 4 Natural History Museum Fribourg, Fribourg, Switzerland

The integration of past, present and future spatial-temporal patterns is crucial in all research areas of biogeography and conservation biology. Combined with the phylogenomics, biogeography, and adaptive genomic variation, we explored the origin, speciation, hybridization, and adaptive evolution of the small Cenozoic relict genus Pterocarya that live in riparian areas with six to eight species. Our results clearly confirm the division of the genus into two monophyletic sections: the Platyptera section and the Pterocarya section. The climate changes during the Early Miocene era coped with the divergence between the two sections. The climate cooling and formation of Gobi Desert in the Middle Miocene epoch caused a split in the continuous distribution of the genus and formation of the disjunction. Focus on East Asia, the phylogeographic break of Pterocarya hupehensis conformed to the boundary of the Sino-Himalayan and Sino-Japanese forests sub-kingdoms. However, in contrast to the nuclear gene, two chloroplast clades within the eastern lineage further diverged along the Yangtze River, and the extensive pollen flow may be the primary factors. Three genetic lineages within P. macroptera: the Qinling-Daba-Tianmu Mountains, Western Sichuan, and Northwest Yunnan lineages, which showed significant signals of isolation by distance (IBD) and isolation by environment (IBE). The identified GEA SNP-related genes were involved in chemical defence and gene regulation and may exhibit higher genetic variation to adapt to the environment. Gradient forest analysis revealed that the genetic variation was mainly shaped by temperature-related variables. A limited adaptive potential was suggested by the high levels of genetic vulnerability in marginal populations. Environmental gradient mainly shaped the population differentiation of P. macroptera. Marginal populations may be at high risk of extinction, and thus proactive management measures, such as assisted gene flow, are required to ensure the survival of these populations.