1. Department of Biosciences Centre for Ecological and Evolutionary Synthesis University of Oslo PO Box 1066 Blindern N‐0316 Oslo Norway
2. Department of Theoretical Biology University of Vienna Althanstrasse 14 1090 Vienna Austria
3. Konrad Lorenz Institute for Evolution and Cognition Research Martinstrasse 12 A‐3400 Klosterneuburg Austria