The Cape element in the Afrotemperate flora: from Cape to Cairo?

The build-up of biodiversity is the result of immigration and in situ speciation. We investigate these two processes for four lineages (Disa, Irideae p.p., the Pentaschistis clade and Restionaceae) that are widespread in the Afrotemperate flora. These four lineages may be representative of the numerous clades which are species rich in the Cape and also occur in the highlands of tropical Africa. It is as yet unclear in which direction the lineages spread. Three hypotheses have been proposed: (i) a tropical origin with a southward migration towards the Cape, (ii) a Cape origin with a northward migration into tropical Africa, and (iii) vicariance. None of these hypotheses has been thoroughly tested. We reconstruct the historical biogeography of the four lineages using likelihood optimization onto molecular phylogenies. We find that tropical taxa are nested within a predominantly Cape clade. There is unidirectional migration from the Cape into the Drakensberg and from there northwards into tropical Africa. The amount of in situ diversification differs between areas and clades. Dating estimates show that the migration into tropical East Africa has occurred in the last 17 Myr, consistent with the Mio-Pliocene formation of the mountains in this area

The bryofloristic elements of southern Africa

A TWINSPAN classification divides the moss flora of southern Africa (South Africa, Namibia, Botswana, Swaziland, and Lesotho) into two main bryofloristic elements: (1) the Xerophytic (south-western) element mainly distributed in the winter rainfall and semi-arid to arid, temperate areas of southern Africa, and (2) the Mesophytic (subtropical) element distributed in more stable, subtropical habitats of the northern, eastern and southern parts of southern Africa. The Xerophytic element is dominated by acrocarpous mosses, including the ephemerals, while the Mesophytic element contains most of the pleurocarpous mosses. The main Xerophytic element is subdivided into the Eastern Highlands and Cape Elements while the Mesophytic element consists of the Afromontane Grassland and Afromontane Forest Elements. The Afromontane Forest Element is the largest bryofloristic element and contains the most southern African moss endemics. The four bryofloristic elements are subdivided into eight subelements: the Eastern Highlands Element into the Mont Aux Sources and Widespread Subelements, the Cape Element into the West Coast and Boland Subelements, the Afromontane Grassland Element into the Disjunct Cape Peninsula and Drakensberg Subelements, and the Afromontane Forest Element into the Widespread Afromontane and Tropical Afromontane Subelements. Many of the bryofloristic elements and distribution centres correspond with phytogeographical elements and centres described for the seed plants of southern Africa. The Afromontane area in the south-western Cape is identified as a bryogeographical hotspot