Résumé
Climatic niche evolution during the diversification of tropical plants has
received little attention in Africa. To address this, we characterized the
climatic niche of >4000 tropical African woody species,
distinguishing two broad bioclimatic groups (forest vs. savanna) and six
subgroups. We quantified niche conservatism versus lability at the genus
level and for higher clades, using a molecular phylogeny of >800
genera. Although niche stasis at speciation is prevalent, numerous clades
individually cover vast climatic spaces suggesting a general ease in
transcending ecological limits, especially across bioclimatic subgroups.
The forest biome was the main source of diversity, providing many lineages
to savanna, but reverse shifts also occurred. We identified clades that
diversified in savanna after shifts from forest. The forest-savanna
transition was not consistently associated with a growth form change,
though we found evolutionarily labile clades whose presence in forest or
savanna is associated respectively with climbing or shrubby species
diversification.