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Central African rain forest dynamics: phylogeography of the small palm genus Podoccocus

Faye Adama (Senegal)

Supervisor: Thomas Couvreur


Recall of project objectives – The aim of my PhD project was to test several predictions related to the forest refugia hypothesis in Central African rain forests using phylogeographic and genetic diversity patterns of the two species of the genus Podococcus. Results should help to better understand population genetic responses to past climate change and test the hypothesis of rain forest refugia in Central Africa. This study is one of the first in Africa combing phylogeographic patterns and paleoclimatic niche modeling to test past evolutionary dynamics of an African TRF plant species.

In our project we aimed to use simple molecular markers to answer our scientific questions, but for having data of high molecular resolution allowing to conduct further temporal analyzes we have used the Next Generation Sequencing method. Initially we planned to undertake traditional sanger sequencing, but we had the opportunity to use NGS. The funds enable us to undertake one MiSeq run to generate full plastome sequences for 50 individuals. The results of this project are currently been included in an article to be submitted to a high impact journal (eg Molecular Ecology).

Study results - still ongoing

  • Using our important molecular data obtained by NGS sequencing we confirm that the two species are genetically different and their divergence time should dated to the start of the Pleistocene.
  • Genetic diversity combined with climate niches inferred for Podoccocus in the past highlighted a general pattern of Pleistocene distribution.
  • Current distribution zones would be both refugia and areas of recent colonization because populations have persisted through time in the same areas.
  • Populations in predicted climatically stable areas (the coast region in North Gabon) showed a significant higher level of unique diversity, suggesting that these populations persisted throughout climatic isolations. These populations should be a priority for conservation in the future.

All results are the subject of a drafted in which IAPT will be acknowledged for his contribution.

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