The diversity, evolution, and conservation of African plants

Africa is home to a remarkable variety of plant life across different ecosystems, but the continent's evolutionary history across the entire landmass is not well understood. A team of researchers has combined a time-calibrated phylogeny representing 93% of African vascular plant genera with data on the continent's distribution to examine phylogenetic diversity, endemism, and diversification rates.

Their findings reveal a significant disconnect between the rate at which species evolve and the amount of evolutionary history they have accumulated across Africa.

The study shows that mountainous, arid, and semi-arid regions serve as hotspots for neo-endemism and high diversification rates, while lowland and humid areas, particularly the Guineo-Congolian zone, are characterized by older lineages with relatively low recent diversification. Surprisingly, several areas with high diversification rates do not coincide with the Global Biodiversity Hotspots, indicating a discrepancy between rapid evolutionary changes and the overall history of the species present in those regions.

The researchers suggest that high net diversification and speciation rates over the past 15 million years were primarily driven by cooling, aridification, and mountain uplift, which created new ecological gradients and isolation barriers. These abiotic changes, combined with lineage-specific traits, have shaped the modern flora of Africa, highlighting conservation gaps, particularly in arid regions that have been overlooked in terms of protection efforts.