1. Department of Biology, Division of Zoology, University of Oslo, P.O. Box 1050 Blindern, N‐0316 Oslo, Norway
2. Department of Animal Science, Agricultural University of Norway, P.O. Box 5025, N‐1432 Ås, Norway
3. Department of Morphology, Genetics and Aquatic Biology, The Norwegian School of Veterinary Science, P.O. Box 8146, Department N‐0033 Oslo, Norway
4. Finnish Game and Fisheries Research Institute, Reindeer Research Station, Fin‐99910 Kaamanen, Finland