1. Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore.
2. International Centre for Tropical Agriculture (CIAT), Asia Regional Office, Pham van Dong Road, Tu Liem District, Hanoi, Vietnam.
3. Department of Economics, School of Global Environmental Sustainability, Colorado State University, Fort Collins, CO 80523–1771, USA.