1. Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Postbus 50, 6700 AB, Wageningen, The Netherlands
2. Instituto de Biología Integrativa de Sistemas (I2SysBio), CSIC-Universitat de València, Parc Cientific UV, Catedrático Agustín Escardino 9, Paterna, Valéncia 46980, Spain
3. The Santa Fe Institute, Santa Fe, 1399 Hyde Park Road, NM 87501, USA