Spatio-Temporal Evolution of Cedreleae (Cedrela, Toona) from Paleocene to Pliocene/Pleistocene

Our study objective is the evolutionary history of the neotropical Meliaceae genus Cedrela (c. 18 species), and the sister clade (Toona) which today is restricted to tropical Asia/Australia, in the light of climatic and geologic changes during the Tertiary. These genera belong to the family Meliaceae, which is one of many plant families that today are restricted to the world's tropical forests, but have Eocene, Oligocene, and Miocene fossils from the northern hemisphere. Sequences from nuclear ITS and plastid loci obtained for all ingroup species and relevant outgroups will be used to infer phylogenetic patterns and divergence times. Preliminary results suggest that (i) crown group diversification in Cedrela started in the Oligocene/Early Miocene and intensified in the Late Miocene and Early Pliocene, and (ii) Central American Cedrela species do not form a clade, implying reentry into Central America after the closure of the Panamanian Isthmus. Newly generated sequences may also be used as barcodes by customs authorities to identify timber. In a second approach we will combine dated molecular phylogenetic trees with species distribution modeling to assess the evolution of the climatic niches to investigate links between climate change and the diversification of Cedrela. The localization of herbarium specimens will be used to infer species distribution ranges. Together with a well documented fossil record, we will evaluate the adequacy of phylogenetic approaches to infer the evolution of species' climatic niches. Temporal coverage: Eocene to Pliocene