1. Scotlands Rural College, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JG, Scotland, U.K.;
2. Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh EH9 3JT, U.K.;
3. Department of Plant and Environmental Sciences, Copenhagen University, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark;
4. Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds vej 10, Aarhus, Denmark; and
5. Edinburgh Genomics, School of Biological Sciences, The University of Edinburgh; Scotland, U.K.