Data from: Phylogeography of African locust bean (Parkia biglobosa) reveals genetic divergence and spatially structured populations in West and Central Africa

The evolutionary history of African savannah tree species is crucial for
the management of their genetic resources. In this study, we investigated
the phylogeography of Parkia biglobosa and its modelled distribution under
past and present climate conditions. This tree species is very valued and
widespread in West Africa, providing edible and medicinal products. A
large sample of 1 610 individuals from 84 populations, distributed across
12 countries in Western and Central Africa, were genotyped using eight
nuclear microsatellites. Individual-based assignments clearly
distinguished three genetic clusters, extreme West Africa (EWA), centre of
West Africa CWA), and Central Africa (CA). Overall, estimates of genetic
diversity were moderate to high, with lower values for populations in EWA
(AR=6.4, HE=0.78 and HO=0.7) and CA (AR=5.9, HE=0.67 and HO=0.61) compared
to populations in CWA (AR=7.3, HE=0.79 and HO=0.75). The overall
population differentiation was found to be moderate (FST=0.09). A highly
significant isolation-by-distance pattern was detected, with a marked
phylogeographic signature suggesting possible effects of past climate and
geographic barriers to migration. Modelling the potential distribution of
the species showed a contraction during the last glaciations followed by
expansion events. The exploratory Approximate Bayesian Computation
conducted suggests a best-supported scenario in which the cluster CWA
traced back to the ancestral populations and a first split between EWA and
CWA took place about 160 000 years BP, then a second split divided CA and
CWA, about 100 000 years BP. However, our genetic data do not enable to
conclusively distinguish among a few alternative possible scenarios.