The Cape flora of South Africa grows in a continental area with many diverse and endemic species. We need to understand the evolutionary origins and ages of such 'hotspots' to conserve them effectively. In volcanic islands the timing of diversification can be precisely measured with potassium-argon dating. In contrast, the history of these continental species is based upon an incomplete fossil record and relatively imprecise isotopic palaeotemperature signatures. Here we use molecular phylogenetics and precise dating of two island species within the same clade as the continental taxa to show recent speciation in a species-rich genus characteristic of the Cape flora. The results indicate that diversification began approximately 7-8 Myr ago, coincident with extensive aridification caused by changes in ocean currents. The recent origin of endemic species diversity in the Cape flora shows that large continental bursts of speciation can occur rapidly over timescales comparable to those previously associated with oceanic island radiations.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. . International Association for Plant Taxonomy (IAPT) is collaborating with JSTOR to digitize, preserve and extend access to Taxon. Chase, M. W.: Phylogenetic analysis of Phylica L. (Rhamnaceae) with an emphasis on island species: evidence from plastid trnL-F DNA and nuclear internal transcribed spacer (ribosomal DNA) sequences. -Taxon 50: 405-427. 2001. -ISSN 0040-0262.The relationships of the island species of Phylica and other genera in Phyliceae (Rhamnaceae) were evaluated using sequences for the plastid trnL intron, the trnL-F intergenic spacer and the internal transcribed spacers of nuclear ribosomal DNA. Both regions provided nearly identical phylogenetic patterns, so they were analysed as a combined matrix. The genera Nesiota and Noltea were found to be palaeoendemic species within the context of the tribe. The island species of Phylica formed a monophyletic group together with the widespread mainland species, P. paniculata. The plesiomorphic, generalist morphology of this group contrasts with the derived morphological characteristics of the majority of mainland species. However, the group occupies a derived position in the phylogenetic trees, thus indicating either a reversal or more likely the retention of these primitive traits.

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