Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway.|Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway.|Centre for Integrative Genetics, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway.|Centre for Integrative Genetics, Department of Animal and Aqucultural Sciences, Norwegian University of Life Sciences, Ås, Norway.|Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway.