Beyond climate: convergence in fast evolving sclerophylls in Cape and Australian Rhamnaceae predates the mediterranean climate

Morphological convergence in mediterranean-type ecosystems (MTEs) has long been interpreted as adaptation to climatic similarities among the five MTEs of the world. Here, we challenge this model using the globally distributed Rhamnaceae. We collected functional trait data (specific leaf area, leaf area, spinescence, leaf phenology, growth form and leaf margin type) and biome data to test for trait convergence in MTEs, for models of trait evolution and ancestral state reconstruction and for the effect of traits on speciation and extinction rates, using a phylogenetic framework. We show that leaf functional traits evolve to three optima, which correspond to (a) the edaphically specialized Australian and Cape MTEs (AC), (b) the mediterranean-type climates, but edaphically normal Chile, California and Mediterranean Basin (CCM), and (c) the non-mediterranean habitats. We find that Rhamnaceae in CCM are predominantly characterized by non-sclerophylly, the ancestral state in Rhamnaceae, and Rh...