1. School of Geography, University of Leeds, Leeds LS2 9JT, UK.
2. Instituto de Pesquisa Ambiental da Amazônia, Avenida Nazaré 669, 66035-170 Belém, Brazil.
3. Woods Hole Research Center, Falmouth, MA 02450, USA.
4. Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.