Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora
1 School of Biological Sciences, Lyle Tower, University of Reading, Whiteknights, Reading RG6 6BX, UK
2 Biosystematics Group, Wageningen UR, & Nationaal Herbarium Nederland, Wageningen University branch, Generaal Foulkesweg 37, 6703 BL Wageningen, The Netherlands
3 Department of Biochemistry, Stellenbosch University, Private Bag X1, 7602 Matieland, South Africa
4 Institut für Spezielle Botanik, Johannes Gutenberg-Universität Mainz, Bentzelweg 2, 55099 Mainz, Germany
5 Department of Botany and Zoology, Stellenbosch University, Private Bag X1, 7602 Matieland, South Africa
6 Royal Horticultural Society Garden Wisley, Woking, Surrey, GU23 6QB, UK
7 Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, UK
8 Institute for Systematic Botany, University of Zürich, Zollikerstrasse 107, CH 8008, Zürich, Switzerland
9 J.C. Parks Herbarium, Department of Biology, Millersville University, Millersville, Pennsylvania 17551, USA
10 Department of Botany, University of Cape Town, Private Bag X3, 7701 Rondebosch, South Africa
11 University of Osnabrueck, Department of Biology/Botany, Barbarastrasse 11, 49069 Osnabrück, Germany
12 The Royal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh EH3 5LR, UK
13 Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, UK
14 The Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
15 UMR C53 PVBMT, CIRAD-Université de la Réunion, 7 chemin de l'IRAT, Ligne Paradis, 97410 Saint Pierre, France
16 School of Biological and Conservation Sciences, University of KwaZulu-Natal, Pr. Bag X01 Scottsville Pietermaritzburg 3209, South Africa
BMC Evolutionary Biology 2011, 11:39 doi:10.1186/1471-2148-11-39Published: 8 February 2011
The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africa's biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years.
Forty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology.
Adaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the flora's extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record.