Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, NO-7491 Trondheim, Norway. Tommy.Jorstad@bio.ntnu.no|Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, NO-7491 Trondheim, Norway. Tommy.Jorstad@bio.ntnu.no|Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, NO-7491 Trondheim, Norway. Tommy.Jorstad@bio.ntnu.no