Affiliation: | Department of Biology, Open University, Milton Keynes, MK7 6AA, U.K.;Centro de Ecología, Universidad Nacional Autónoma de México, Apdo. Postal 70-275, 04510 México D.F., Mexico;Archbold Biological Station, P. O. Box 2057, Lake Placid, FL 33852, U.S.A., email |