1. Department of Biological and Environmental Sciences; University of Jyvaskyla; PO Box 35 FI-40014 University of Jyvaskyla Finland
2. Center for Macroecology Evolution and Climate; Natural History Museum of Denmark; University of Copenhagen; Universitetsparken 15, Building 3 DK-2100 Copenhagen Denmark
3. Department of Economics; University of Oulu; PO Box 4600 FI-90014 Oulu Finland
4. Natural Resources Institute Finland, Oulu; University of Oulu; Paavo Havaksen tie 3, PO Box 413 FI-90014 Oulu Finland
5. Systems Research Institute; Polish Academy of Sciences; Newelska 6 01-447 Warsaw Poland
6. Department of Mathematical Information Technology; University of Jyvaskyla; PO Box 35 (Agora) FI-40014 University of Jyvaskyla Finland