Format: ORAL

Ze-Long Nie 1, Ying Meng 1, Meng-Hua Zhang 1, Luke Sparreo 2, Alicia Talavera 3,Jun Wen 3

1 College of Biology and Environmental Sciences, Jishou University, Jishou, Hunan 416000, China. 2 Department of Botany, Connecticut College, New London, CT 06320, U.S.A. 3 Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, U.S.A.

The evolutionary patterns and processes driving ecological transition and diversification between tropical and north temperate biomes are complex and remain poorly understood in the Northern Hemisphere flora. Moreover, it is becoming clear that introgression is an important driving force of speciation in plant diversity. Here, we applied phylogenetic and biogeographic analyses to account for both introgression and incomplete lineage sorting based on genomic data from two charismatic lineages of the Northern Hemisphere, the tribe Viteae (the Ampelocissus-Vitis group) of Vitaceae and Magnolia of Magnoliaceae. Biogeographic inference and fossil evidence suggest that the ancestors of Viteae were widely distributed from North America to Europe during the Paleocene to the Eocene, followed by widespread extinction and survival of relicts in the tropical New World. During the climate warming in the early Miocene, an ancestor migrated northward from the refugia with subsequent diversification in North America and Eurasia. Similarly, Magnolia had once been widely distributed in the Northern Hemisphere in the early Palaeogene followed with extensive extinction and southward retreat to the low-latitude regions during the middle to late Eocene cooling climate. Magnoliaceae had been well diversified in the tropical regions with less development during the transition back to the temperate regions. Meanwhile, we found strong evidence for widespread incongruence and reticulate evolution among nuclear genes within both recent and ancient lineages in the Ampelocissus-Vitis clade and Magnolia during their biome transitions and diversification in the Northern Hemisphere. The scenario we report here may represent a transition model between tropical and temperate regions in general for flowering plants that adapted to the global climate cooling and fluctuation in the Northern Hemisphere.