A rich diversity of rainforest tress, as in the Ivindo National Park in Gabon © O. Hardy

A large phylogeny of African rainforest tree species will be produced, using chloroplast markers, analyzing ca. 2000 individuals from 700 Guineo-Congolian species. This comprehensive phylogeny will be time-calibrated using fossil evidence, to estimate divergence times between the studied populations, subspecies or sister species.

Genomic tools to analyze DNA and reconstruct the evolutionary history of rainforest trees © J. Migliore

The phylogeographical patterns of 10 forest-dwelling trees will be described at the Guineo-Congolian scale, using microsatellites markers. Analyzing the spatial distribution of gene pools and their diversity constitutes a key step before testing for past population demographic changes and alternative scenarios of gene pool differentiation. We will complete sampling and genotyping by adding plant material from the Congo basin and from Upper Guinea, including 15 African rainforest tree species (or complexes) representative of distinct functional groups.

Studying Cameroon rainforest through genomic tools, a new challenge…© O. Hardy © J. Migliore

Next Generation Sequencing (NGS) allows more precise inferences than microsatellite genotyping thanks to their much higher genome coverage and limited homoplasy. However, protocols adequate for phylogeographic studies are still to be optimized, especially for Annonaceae and Fabaceae species. These data will provide (i) more precise estimation of divergence time between gene pools using a coalescence approach, (ii) potential molecular signatures of genomic regions under selection.