1. Department of Biology, McGill University , 1205 ave Docteur Penfield, Montreal, Quebec H3A 1B1 , Canada
2. Department of Geography, University of Zurich , Winterthurerstrasse 190, 8057 Zurich , Switzerland
3. Redpath Museum, McGill University, 859 Sherbrooke St West , Montreal, Quebec H3A 0C4 , Canada