Format: ORAL

Zhi-Duan Chen1, Dan-Xiao Peng1, Hai-Hua Hu1, Li-Min Lu1, Russell Barrett2, Jun Wen3

1 Institute of Botany, Chinese Academy of Sciences, Beijing, China 2 National Herbarium of New South Wales, Australian Botanic Garden, Australia 3 Department of Botany, Smithsonian Institution, Washington, USA

The Asia-Australasia floristic exchanges have long attracted the attention from evolutionary biologists with its complex geologic background and remarkable associated biodiversity.The rich floras of Asia and Australasia converge at the unique Wallacea transition zone, which is noted for the well-known Wallaces Line and its outstanding tropical biodiversity. Since the early 19th century, critical insights have been proposed concerning the extent, timing, and routes of the Asia-Australasia floristic exchange, as well as characteristics of the exchanged elements and ecological filters of the exchange processes. We present the early exchanges dated to the supercontinent, the recent affinities during the Quaternary glacial fluctuation, and even the invasive biotic dynamics in the Anthropocene. By integrating distribution data and evolutionary information of plant lineages within the Asia-Australasiaconvergent region, southwestern Asia showed the highest plant richness, while southern Asia to eastern Australia showed the highest the phylogenetic diversity, indicating that the flora of southern Asia to eastern Australiahas together preserved ancient and diverse evolutionary history with frequent interchanges within the region. To better reflect the relationships among florasinside the region, we revisited the regionalization inside theregionunder a robustphylogenetic framework of the global seed plants and delineatedthe three phytogeographic areas: the Asia continent and Sunda region,the Wallacea region, and the Sahul region. Wefound the dispersal exchange among these three areas dominated in a time period after the middle Miocene, consistent to the time when northern and southern shelves in Southeast Asia collidedandthe migration showed significant asymmetry with the southward dispersal exceeding the northward dispersal.We expectthe understanding of the evolutionary history of Asia-Australia florawould shed light on the development history of global biodiversity distributionpatternand provide the theory foundation for biodiversity conservation in additionto new understanding in the biogeography.