1. Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE–752 36 Uppsala, Sweden
2. Finnish Game and Fisheries Research Institute, Oulu Game and Fisheries Research, Tutkijantic 2A, FIN–90570 Oulu, Finland
3. Laboratory of Parasitology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
4. GrimsöResearch Station, Swedish University of Agricultural Sciences, SE–730 91 Riddarhyttan, Sweden
5. Hedmark College, Department of Forestry and Wilderness Management, N–2480 Koppang, Norway