1. Functional Ecology of Plants, Institute of Biology and Environmental Sciences University of Oldenburg P.O. Box 2503, D‐26111 Oldenburg Germany
2. Functional Morphology and Biomechanics Zoological Institute, Kiel University, Am Botanischen Garten 9 24118 Kiel Germany
3. Smithsonian Tropical Research Institute, Balboa Panama Republic of Panama