Format: ORAL

Flix Forest1, Jonathan F. Colville2, Colin Beale3, Brent Mishler4, Andrew Thornhill5, G. Anthony Verboom6, Richard M. Cowling7

1 Royal Botanic Gardens, Kew, Richmond, Surrey, UK 2 Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa 3 Department of Biology, University of York, York, UK 4 University & Jepson Herbaria, Dept. of Integrative Biology, University of California, Berkeley, USA 5 N.C.W. Beadle Herbarium, University of New England, Armidale, New South Wales, Australia 6 Department Biological Sciences, University of Cape Town, Cape Town, South Africa 7 African Centre for Coastal Palaeoscience, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa

The Greater Cape Floristic Region (GCFR) of South Africa is a small area found in the southwestern corner of the African continent and comprising an incredible floral diversity (ca 11,500 species, ca 75% endemic). Small-leaved sclerophyllous shrubs and geophytes are the predominant growth forms in the region while tree and annual species represent only a small proportion of the flora. Furthermore, the floristic composition of the region is very distinctive with families such as Iridaceae, Aizoaceae, Ericaceae, Proteaceae and Restionaceae dominating, all of which are minor groups in other floras of the world. Understandably, this diversity has attracted a lot of speculation as to which environmental and/or ecological factors may be the prevailing drivers explaining the uniqueness of the region. This contribution reports on ongoing studies focussing on large-scale spatial phylogenetic patterns within the region. First, we present a spatial phylogenetic analysis using phylogenetic diversity and phylobetadiversity metrics based on a set of species-level phylogenetic trees and fine-scale species distribution modelling comprising all species found in the GCFR. In particular, we investigate the west-east decreasing longitudinal gradient in plant diversity observed in the region, termed the Levyns Law. We explore the predictions made to explain this gradient by the age and area (i.e. high diversity is the result of biome and climate stability over evolutionary times) and ecological opportunity (high diversity is the result of increased ecological heterogeneity) hypotheses. Secondly, we examine the phylogenetic endemism patterns in the GCFR using Categorical Analysis of Neo- and Paleo-Endemism (CANAPE) to characterize local centres of endemism. We compare these species-level results with preliminary analyses performed at the genus-level to observe the effects of using different taxonomic levels. All these diversity measures are used in concert to try to understand both the origin of this extraordinary biodiversity hotspot and to prioritize conservation efforts.