History and evolution of the afroalpine flora: in the footsteps of Olov Hedberg

Abstract The monumental work of Olov Hedberg provided deep insights into the spectacular and fragmented tropical alpine flora African sky islands. Here we review recent molecular niche modelling studies re-examine Hedberg’s hypotheses conclusions. Colonisation started when mountain uplift established harsh diurnal climate with nightly frosts, accelerated throughout last 5 Myr (Plio-Pleistocene), resulted in a rich local endemics. Recruitment was dominated by long-distance dispersals (LDDs) from seasonally cold, remote areas, mainly Eurasia. only rarely followed substantial diversification. Instead, most larger genera even species colonised afroalpine habitat multiple times independently. Conspicuous parallel evolution occurred among mountains, e.g., gigantism Lobelia Dendrosenecio dwarf shrubs Alchemilla . Although ~ 8 treeline 1000 m lower than today during Last Glacial Maximum, genetic data suggest that shaped strong intermountain isolation interrupted rare LDDs rather ecological connectivity. new evidence points to much younger more dynamic island scenario envisioned Hedberg: is unsaturated fragile, it repeatedly disrupted Pleistocene oscillations, harbours taxonomic diversity unique but severely depauperated frequent bottlenecks cycles colonisation, extinction, recolonisation. level intrapopulation variation alarmingly low, many may be vulnerable extinction because warming increasing human impact.