1. Centre for Coastal Palaeoscience, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa
2. Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, South Africa
3. Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Rondebosch, 7701, South Africa
4. Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK