Format: ORAL

Thomas L. P. Couvreur 1 Andrew J. Helmstetter 1 ,Kevin Bethune1, Narcisse G. Kamdem 2; Bonaventure Sonké 2

1 Institut de Recherche pour le Développement (IRD), UMR-DIADE, BP 64501, F-34394, Montpellier cedex 5, France 2 Université de Yaoundé I, Ecole Normale Supérieure, Département des Sciences Biologiques, Laboratoire de Botanique systématique et d’Ecologie, B.P. 047, Yaoundé, Cameroon

Central African rain forests are mega diverse and harbor the worlds second largest expanse of this biome. Yet, how plant species have adapted to past climate change remains understudied. Palms might not be that diverse in this region, but they are nevertheless omnipresent. Here, we infer the evolutionary and demographic dynamics of three co-distributed palm species using comparative phylogeography based on hundreds of nuclear markers. In addition, we contrast our results with four tree species of Annonaceae, an equally important component on rain forests in Africa. For all species we estimated population variation and the temporal origin of this structure using dated phylogenetic trees. Finally, we explicitly tested how different environmental factors such as soil, climate stability and geography have shaped intraspecific genetic variation in each of our species. Levels of genetic variation varied among palms and Annonaceae, all showing some level of structure. Divergence between populations emerged primarily during the Pleistocene, but were rarely concordant. Demographic trends ranged from repeated contraction and expansion to continuous growth. Furthermore, patterns in genetic variation were linked to disparate environmental factors, including climate, soil, and habitat stability. Using a strict refugia model to explain past TRF dynamics in central Africa is too simplistic. Instead, individualistic evolutionary responses to Pleistocene climatic fluctuations have shaped patterns in genetic diversity in central African rain forests. Overall our results suggest that predicting the evolutionary responses of TRF plant diversity under climate change will be challenging. More emphasis is needed on individual species ecology if conservation of this incredible diversity is to be effective.