1. Instituto de Pesquisa Ambiental da Amazônia (IPAM), Av. Nazaré 669, Belém 66035-170, Brazil
2. Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02450, USA
3. Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305-4101, USA
4. Department Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA