Davies, T. JonathanSmith, G.F. (Gideon Francois), 1959-Bellstedt, Dirk U.Boatwright, James S.Bytebier, BennyCowling, R.M. (Richard Mark)Forest, FelixHarmon, Luke J.Muasya, A. MuthamaSchrire, Brian D.Steenkamp, YolandeVan der Bank, MichelleSavolainen, Vincent2012-05-072012-05-072011-05-24Davies TJ, Smith GF, Bellstedt DU, Boatwright JS, Bytebier B, et al. (2011) Extinction Risk and Diversification Are Linked in a Plant Biodiversity Hotspot. PLoS Biol 9(5): e1000620. DOI: 10.1371/journal.pbio.1000620.1544-917310.1371/journal.pbio.1000620http://hdl.handle.net/2263/18675It is widely recognized that we are entering an extinction event on a scale approaching the mass extinctions seen in the fossil record. Present-day rates of extinction are estimated to be several orders of magnitude greater than background rates and are projected to increase further if current trends continue. In vertebrates, species traits, such as body size, fecundity, and geographic range, are important predictors of vulnerability. Although plants are the basis for life on Earth, our knowledge of plant extinctions and vulnerabilities is lagging. Here, we disentangle the underlying drivers of extinction risk in plants, focusing on the Cape of South Africa, a global biodiversity hotspot. By comparing Red List data for the British and South African floras, we demonstrate that the taxonomic distribution of extinction risk differs significantly between regions, inconsistent with a simple, trait-based model of extinction. Using a comprehensive phylogenetic tree for the Cape, we reveal a phylogenetic signal in the distribution of plant extinction risks but show that the most threatened species cluster within short branches at the tips of the phylogeny—opposite to trends in mammals. From analyzing the distribution of threatened species across 11 exemplar clades, we suggest that mode of speciation best explains the unusual phylogenetic structure of extinction risks in plants of the Cape. Our results demonstrate that explanations for elevated extinction risk in plants of the Cape flora differ dramatically from those recognized for vertebrates. In the Cape, extinction risk is higher for young and fast-evolving plant lineages and cannot be explained by correlations with simple biological traits. Critically, we find that the most vulnerable plant species are nonetheless marching towards extinction at a more rapid pace but, surprisingly, independently from anthropogenic effects. Our results have important implications for conservation priorities and cast doubts on the utility of current Red List criteria for plants in regions such as the Cape, where speciation has been rapid, if our aim is to maximize the preservation of the tree-of-life.en© 2011 Davies et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Biodiversity hotspotExtinction riskPlants -- Extinction -- South Africa -- Cape of Good HopeBiodiversity conservation -- South Africa -- Cape of Good HopeMass extinctions -- South Africa -- Cape of Good HopeArticle