1. Norwegian Institute for Nature Research; P.O. Box 5685 Sluppen Trondheim NO-7485 Norway
2. ICTEAM/UCL; Université catholique de Louvain; Louvain-la-Neuve Belgium
3. Department of Biological Sciences; University of Alberta; Edmonton T6G 2E9 Canada
4. Department of Biology; Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; Trondheim NO-7491 Norway
5. Department of Animal and Human Biology; Sapienza University; Viale dell'Università 32 Rome 00185 Italy