1. Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, 750 07 Uppsala, Sweden.
2. Spatial Foodweb Ecology Group, Department of Agricultural Sciences, PO Box 27, (Latokartanonkaari 5), FI-00014 University of Helsinki, Finland.
3. Centre for Ecology and Evolution in Microbial model Systems (EEMiS), Department of Biology and Environmental Science, Linnaeus University, 39182 Kalmar, Sweden.