Hope College Biology

Community-level Consequences of Chemical Defense in Tropical Pioneer Plant Seeds

Tropical rainforests are legendary for their biological diversity and for the complexity of interactions among their species. The interactions between animals and plants are especially prominent – animals are important as pollinators, seed dispersers and seed predators, and plants are under strong selection pressure to reinforce the positive interactions with animals and to weaken the negative ones. “Pioneer” plants – those that specialize on colonizing recently disturbed patches of forest but which cannot compete in the shaded understory – constitute a model system in which to study tropical plant-animal interactions. My research group seeks to understand how seed dispersers, seed predators, microbial pathogens, and physical disturbance interact to influence the demography of tropical pioneer plants and thus the maintenance of forest structure and species composition. Specific research projects concentrate on one or more of the following: 1) elucidating the spatial patterns of seed dispersal by birds and bats in Costa Rica; 2) estimating forest disturbance rates and demographic patterns of pioneer plants from permanent study plots in Monteverde, Costa Rica; 3) combining data on plant demography and forest disturbance rates with mathematical models that address the evolution of life history traits (“how to be a pioneer plant”) and the potential consequences of climate change for forest composition; and 4) characterizing the chemical defenses of pioneer plant seeds that allow them to persist in forest soils for decades in the face of predators and pathogens. I am especially interested in questions that encompass several levels of biological organization or that combine the approaches of other disciplines (e.g., mathematics, computational science, and organic chemistry) with those of ecology. For example, students involved in research on seed chemistry will employ a variety of chemical separation and analysis techniques, as well as fungal and arthropod toxicity bioassays, to isolate and identify the toxic compounds. Students involved in research on forest dynamics and plant demography will employ tools from mathematics (e.g., linear algebra) and computational science (e.g., MATLAB). Students working during the summer will have the opportunity to collect field data in Costa Rica. All students will participate in hypothesis formation, experimental design, data acquisition and analysis. They will routinely read and discuss scientific literature, and they will have ample opportunity to develop skills for writing scientific papers and delivering scientific presentations.

Representative Publications:

• Murray, K.G., K. Winnett-Murray, J. Roberts*, K. Horjus*, W.A. Haber, W. Zuchowski, M. Kuhlmann*, and T.M. Long-Robinson*. In press. The roles of disperser behavior and physical habitat structure in regeneration of post-agricultural fields. Chapter 8, in: R. Myster [ed.]. Post-Agricultural Succession in the Neotropics. Springer U.S., New York.
• Veldman, J.W.*, K.G. Murray, A.L. Hull*, J.M. Garcia-C., W.S. Mungall, G.B. Rotman*, M.P. Plosz*, and L.K. McNamara*. 2006. Chemical Defense and the Persistence of Pioneer Plant Seeds in the Soil of a Tropical Cloud Forest. Biotropica. 39: 87-93.
• Murray, K. G., S. Kinsman, and J. Bronstein. 2000. Plant-animal interactions. In Monteverde: Ecology and Conservation of a Tropical Cloud Forest. Oxford University Press, New York. Edited by N. M. Nadkarni and N. T. Wheelright. Pp. 245-302
• Murray, K.G., and J. Mauricio Garcia-C. 2002. Contributions of seed dispersal and demography to recruitment limitation in a Costa Rican cloud forest. Pp. 323-338, in: Levey, D. J., W. R. Silva, and M. Galetti. (eds) Seed dispersal and frugivory: Ecology, evolution, and conservation. CABI Publishing, Wallingford, UK
• Murray, K.G. 1988. Avian seed dispersal of three neotropical gap-dependent plants. Ecological Monographs 58: 271-298.
• Murray, K.G., S. Russell*, C.M. Picone*, K. Winnett-Murray, W. Sherwood*, and M.L. Kuhlmann*. 1994. Fruit laxatives and seed passage rates in frugivores: consequences for plant reproductive success. Ecology 75: 989-994.
• Murray, K.G. 2000. The importance of different bird species as seed dispersers. Pp. 294-295, in: N.M. Nadkarni and N.T. Wheelwright [eds]. Monteverde: Ecology and Conservation of a Tropical Cloud Forest. Oxford University Press, New York.

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