1 School of Geosciences, Institute of Geography, University of Edinburgh, Edinburgh EH8 9XP, UK. Electronic address: marisa.wilson@ed.ac.uk.
2 Global Academy of Agriculture and Food Security, University of Edinburgh, Edinburgh EH8 9XP, UK; The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH8 9XP, UK; The Roslin Institute, University of Edinburgh, Edinburgh EH8 9XP, UK.