1. Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
2. The Swiss Institute of Bioinformatics, Quartier Sorge – Batiment Genopode, 1015 Lausanne, Switzerland
3. The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
4. 147 Jefferson Road, Princeton, NJ 08540, USA