1. Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary SciencePO Box 8146, Departmental Division, 0033 Oslo, Norway
2. Norwegian Institute for Nature ResearchTungasletta 2, 7485 Trondheim, Norway
3. Finnish Game and Fisheries Research Institute, Reindeer Research Station99910 Kaamanen, Finland
4. Department of Animal and Aquacultural Sciences, Norwegian University of Life SciencesPO Box 5003, 1432 Ås, Norway
5. Department of Geography, University of CambridgeDowning Place, Cambridge CB2 3EN, UK
6. Department of Evolutionary Biology, Uppsala University75236 Uppsala, Sweden