Tropical Biology Section
Westbrook, Jared , Kitajima, Kaoru , Wright, S. Joseph .
Patterns of silica and fiber accumulation in the leaves of 400 neotropical woody species: physical defense in a phylogenetic context.
The physical fortification of leaves is an important anti-herbivore defense in lowland tropical rainforests. Species with leaves high in fiber (cellulose, hemicellulose, and lignin) have high survival rates, yet relatively low rates of growth. Silica may also contribute to physical defense, yet little is known about silica accumulation among tropical woody taxa. Silica accumulation incurs less energetic costs than fiber-based defenses, and may partially circumvent the growth versus defense tradeoff. We examine the relative contribution of silica and fiber to leaf toughness for ~400 woody species from the 50-ha forest dynamics plot on Barro Colorado Island, Panama. Species sampled include canopy trees, sub-canopy trees, shrubs, and lianas. Sun and shade leaves were collected from 6-12 randomly selected individuals of each species. The distribution of foliar silica content (mg SiO2 g-1 leaf dry mass) among species is highly positively skewed with a median of 6 mg g-1, average of 13.67 mg g-1, and maximum of 109 mg g-1. Silica accumulation in leaves is non-random with respect to phylogeny. Fabaceae (subfamilies: Faboideae and Mimosoideae), Piperaceae, Malvaceae (subfamily: Tilioideae), and Myrtaceae contained species with high foliar silica contents. Phylogenetic relationships among sampled species were estimated in order to assess evolutionary and ecological relationships among leaf traits that contribute to variation in physical defense of leaves.
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1 - University of Florida, Department of Biology, P.O. Box 118526, Gainesville, Florida, 32611-8526, U.S.A.
2 - Smithsonian Tropical Research Institute, Box 0843-03092, Balboa, Ancon, Republic of Panama
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM