Computational and Molecular Population Genetics (CMPG) laboratory, Institute of Ecology and Evolution, University of Berne, Baltzerstrasse 6, 3012 Berne, Switzerland. heidi.lischer@iee.unibe.ch|Computational and Molecular Population Genetics (CMPG) laboratory, Institute of Ecology and Evolution, University of Berne, Baltzerstrasse 6, 3012 Berne, Switzerland. heidi.lischer@iee.unibe.ch