ON THE NATURE OF GONDWANAN SPECIES FLOCKS - DIVERSITY OF PROTEACEAE IN MEDITERRANEAN SOUTH-WESTERN AUSTRALIA AND SOUTH-AFRICA

The Proteaceae, a Gondwanan family, are richly represented in South Af rica's Cape Floristic Region (CFR) (331 species, 14 genera) and Austra lia's South West Botanical Province (SWBP) (682 species, 16 genera). B oth of these regions have mediterranean-type climates, infertile soils , similar geomorphic and climatic histories, and show strong convergen ces in plant form and function. There are many similarities in the pat terns and ecological correlates of diversity in the CFR and SWBP Prote aceae. First, both floras are overwhelmingly endemic, with many large genera and correspondingly high species to genus ratios, indicating ma ssive in situ diversification (species flocks). Second, on both contin ents, high habitat (mainly edaphic) specialisation leads to similar le vels of beta diversity. Third, most species are non-sprouters (i.e. ki lled by fire) and of intermediate size. There are, however, several di vergences in these patterns and correlates. First, in the SWBP, Protea ceae invariably emerge as one of the largest families in florulas, whe reas they occupy a much lower rank in the CFR. Second, species numbers in the SWBP peak in landscapes having intermediate levels of annual r ainfall, whereas CFR Proteaceae diversity peaks in the wettest areas. Third, local diversity is higher in the SWBP where Proteaceae have exp loited a wider array of temporal and spatial habitats than in the CFR. Fourth, despite lower environmental heterogeneity in the SWBP, gamma (geographical) diversity is higher there. Fifth, as a result of higher local and gamma diversity, regional richness in the SWBP is more than double that of the CFR. Finally, sprouting, serotiny, bird-pollinatio n and tall stature are proportionally more important traits in the SWB P than the CFR where most species are low, non-sprouting, myrmecochoro us, insect-pollinated shrubs. Subtle differences in the historical and contemporary climates of the two regions have resulted in different p rocesses leading to the origin of these species flocks. In the CFR, mi lder conditions have favoured non-sprouters (short generation times): species have accumulated largely as a result of lineage turnover. Hars her conditions in the SWBP have favoured sprouters: here species have accumulated as a result of both persistence and turnover.