Topography as a driver of diversification in the Cape Floristic Region of South Africa

• DOI: 10.1111/nph.13342
• Publication Date: 2015-02-24T13:03:39Z
• Authors: G. Anthony Verboom; Nicola G. Bergh; Sarah A. Haiden; Vera Hoffmann; Matthew N. Britton
• Keywords: Vicariance; Elevation (ballistics); Cape; Genetic algorithm

Summary The rugged topography of the Cape Floristic Region ( CFR ), South Africa, is frequently invoked to explain spectacular radiation flora, but mechanisms involved remain unclear. Where recent authors emphasize importance elevation gradients as stimuli for ecological speciation, earlier workers stressed role an isolating mechanism, particularly in montane lineages. Using six plant lineages, we tested whether niches are phylogenetically conserved. We then assessed high‐elevation species more consistently range‐restricted than low‐elevation species, and sisters show stronger range exclusivity (allopatry) weaker phenotypic differentiation, suggestive nonecological speciation. Elevation tend be Also, potentially explaining generally sisters. While zone less homogeneous ecologically, data required demonstrate that sister differentiation. Topographic complexity promotes geographical isolation at high elevations, thereby providing opportunities nonecological, vicariant recognizing need additional data, suggest upland lowland floras may differ with regard predominant speciation mode.