The biodiversity hotspot as evolutionary hot-bed : spectacular radiation of Erica in the Cape Floristic Region

Pirie, M. D. ; Oliver, E. G. H. ; De Kuppler, A. Mugrabi ; Gehrke, B. ; Le Maitre, N. C. ; Kandziora, M. ; Bellstedt, D. U. (2016-09-17)

CITATION: Pirie, M. D., et al. 2016. The biodiversity hotspot as evolutionary hot-bed: spectacular radiation of Erica in the Cape Floristic Region.BMC Evolutionary Biology, 16:190, doi:10.1186/s12862-016-0764-3.

The original publication is available at https://bmcevolbiol.biomedcentral.com

Article

Background: The disproportionate species richness of the world’s biodiversity hotspots could be explained by low extinction (the evolutionary “museum”) and/or high speciation (the “hot-bed”) models. We test these models using the largest of the species rich plant groups that characterise the botanically diverse Cape Floristic Region (CFR): the genus Erica L. We generate a novel phylogenetic hypothesis informed by nuclear and plastid DNA sequences of c. 60 % of the c. 800 Erica species (of which 690 are endemic to the CFR), and use this to estimate clade ages (using RELTIME; BEAST), net diversification rates (GEIGER), and shifts in rates of diversification in different areas (BAMM; MuSSE). Results: The diversity of Erica species in the CFR is the result of a single radiation within the last c. 15 million years. Compared to ancestral lineages in the Palearctic, the rate of speciation accelerated across Africa and Madagascar, with a further burst of speciation within the CFR that also exceeds the net diversification rates of other Cape clades. Conclusions: Erica exemplifies the “hotbed” model of assemblage through recent speciation, implying that with the advent of the modern Cape a multitude of new niches opened and were successively occupied through local species diversification.

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