1. Department of Biology; Franklin and Marshall College; PO Box 3003 Lancaster PA 17603 USA
2. Department of Natural Resources and the Environment; University of New Hampshire; 114 James Hall Durham NH 03824 USA
3. Centro de Ciencias de la Atmósfera; Universidad Nacional Autónoma de México; Ciudad de México DF 04510 México
4. Department of Integrative Biology; University of California at Berkeley; Valley Life Sciences Building Berkeley CA 94720 USA
5. School of Forestry and Environmental Studies; Yale University; 195 Prospect Street New Haven CT 06511 USA