African geoxyles evolved in response to fire; frost came later

摘要: It has been proposed in separate studies that fire or frost were the critical selective agents evolution of subshrub geoxyles (SGs) African subtropical grasslands. We attempt to resolve this controversy by examining SGs among entire genus Protea is widespread throughout southern/central Africa. show are not confined grasslands but occur a wide range non-forest vegetation types, including mediterranean shrublands. SG proteas arose 1–11 million years ago their multiple origins other geoxyles, confounded strong intraspecific variability grassland species, makes it impossible identify ancestral growth form. conclude evolutionary history occurred under lightning-prone conditions promoted and essentially frost-free; exposure limited certain elevated locations more recent times. This supported many having pyrogenic flowering lack seed storage species.