1. Department of Biology; Duke University; 130 Science Drive Durham North Carolina 27701 USA
2. Department of Ecology, Evolution and Environmental Biology; Columbia University; 1200 Amsterdam Avenue New York City New York 10027 USA
3. Department of Biology; Barnard College; Columbia University; New York City New York 10027 USA
4. Department of Environmental Sciences; University of Puerto Rico; Río Piedras Campus San Juan Puerto Rico 00936 USA
5. Centre for Ecology & Hydrology; Bush Estate Penicuik; Midlothian EH26 0QB United Kingdom