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Tracking geobiological linkages between speciation and landscape
evolution through space and time – Are plants timekeepers of
formative events in the geomorphic history of the Cape Fold Belt?
V Hoffmann 1,2 , F.P.D. Cotterill 2 , G.A. Verboom 3
1. Botany Department, University of Cape Town, South Africa, vera.hoffmann@uct.ac.za
2. Africa Earth Observatory Network (AEON), Department of Geosciences, Department of Molecular and Cell
Biology, University of Cape Town, South Africa, fenton.cotterill@uct.ac.za
3. Botany Department, University of Cape Town, South Africa, tony.verboom@uct.ac.za
ABSTRACT
The southern tip of the African continent (the Cape Floristic Region) hosts a diverse and highly endemic flora,
whose distribution coincides closely with the Cape Fold Belt (CFB) of mountainous terrain. The geomorphological
evolution of the CFB is poorly understood, not least because the region awaits low temperature thermochronology
studies. Moreover, despite several theories that focus on palaeo-climatic forcing, the causes of “hyper-endemism”
of the Cape flora remain enigmatic. Most recently, Cowling et al. (2008) hypothesized that the geomorphological
evolution of the CFB could have driven pulses of speciation since the Mid-Cenozoic, such that the origin of new
landscapes fostered the origin of local endemics restricted to habitat patches which are characterized by particular
lithological/edaphic conditions. Teasing apart these environmental controls will enable us to test the spatial and
temporal aspects of ‘substrate-tracking’ by plants through a timescale of geomorphological evolution. This study
uses a cross-disciplinary synthesis of time-calibrated plant phylogenies, detailed spatial distribution maps of
individual taxa and fine-scale lithology/climate datasets to evaluate geobiological history of selected fynbos clades;
our key question asks whether formative events in the geomorphological evolution of the CFB created new
opportunities for speciation events and/or range expansions for these Cape plant species. The ability to date these
events with a molecular clock on plant phylogenies can not only resolve the turnover of floral habitats, but is
expected to provide novel insights into first appearances of particular geomorphological conditions in the CFB.
KEYWORDS: Cape Floristic Region, Cape Fold Belt, geomorphology, speciation, molecular dating
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