1. Department of Animal Ecology, Institute of Biology, University of Leiden, PO Box 9516 2300 RA Leiden, The Netherlands
2. Molecular and Evolutionary Ecology Group, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK
3. Institute of Zoology, Department of Biology, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland
4. EAWAG Center for Limnology, Seestrasse 79, CH-6047 Kastanienbaum, Switzerland
5. Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE 75236 Uppsala, Sweden
6. Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
7. Tanzanian Fisheries Research Institute, Mwanza Centre, PO Box 475 Mwanza, Tanzania
8. School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK