1. Department of Genetic Ecology, Institute of Botany Academy of Sciences of Czech Republic Zamek 1 Průhonice 25243 Czech Republic
2. Wageningen Environmental Research (Alterra) P.O. Box 47 Wageningen NL‐6700 AA The Netherlands
3. Experimental Plant Ecology Radboud University Nijmegen P.O. Box 9010 Nijmegen 6500 GL The Netherlands
4. Royal Institute of Technology Stockholm SE‐100 44 Sweden
5. Centre d'Ecologie et des Sciences de la Conservation (CESCO‐UMR 7204) Sorbonne Universités‐MNHN‐CNRS‐UPMC CP51, 55‐61 rue Buffon Paris 75005 France
6. University Rennes 1 Centre National de la Recherche Scientifique, Research Unit "Ecosystèmes, Biodiversité, Evolution" Evolution (UMR 6553), Campus Beaulieu, Bâtiment 14 A Rennes 35042 France