Format: ORAL

Xiao-Quan Wang

State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, the Chinese Academy of Sciences, Beijing , China

Reconstructing the phylogenetic history of organisms and understanding what determines the distribution of species diversity remain challenging in evolutionary biology and ecology. This is particularly true for gymnosperms, which comprise only 13 families and a little more than 1,000 species. Although greatly outnumbered by the species of angiosperms, gymnosperms have huge ecological and economic value, of which conifers (about 615 species) constitute approximately 39% of the worlds forests. In addition, the Northern Hemisphere conifers do not follow a latitudinal diversity gradient and show a unique distribution pattern, i.e., most species are distributed in mountainous areas at middle latitudes. It is of great interest to investigate the spatiotemporal evolution of gymnosperms, especially conifers. In recent rears, we have used phylotranscriptomics to robustly reconstruct the phylogeny of gymnosperms at both higher (interfamilial and intergeneric) and lower (interspecific) taxonomic levels, and employed multidisciplinary approaches to reveal the mechanisms underlying diversification and global distribution of conifers, including Gnetales. Our studies indicate: (1) Podocarpaceae originated in Gondwana in the late Triassic, and both vicariance and dispersal contributed to its current biogeographic patterns; (2) Cupressaceae very likely originated in Asia in the Triassic, and geographic isolation caused by continental separation drove the vicariant evolution of the two subfamilies Cupressoideae and Callitroideae in the northern and southern hemispheres, respectively; (3) The mid-latitude region has provided an evolutionary museum for global pines, topography played a primary role in pine diversification, and the aridity index was decisive for the niche rate shift; and (4) Ephedra very likely originated in the Tethys coast during the late Cretaceous, and the South American Ephedra species have a single origin by dispersal from Mexico or North America. Our study highlights the importance of integrating phylogenomic and ecological approaches to address evolution of biological groups at the global scale.