1. Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology; University of Oslo; P.O. Box 1066 Blindern; N-0316; Oslo; Norway
2. Norwegian Institute for Nature Research; P.O. Box 5685 Sluppen; N-7485; Trondheim; Norway
3. Norwegian Water Resources and Energy Directorate; P.O. Box 5091 Majorstua; N-0301; Oslo; Norway