DISSERTATION RESEARCH: Ecological Costs and Benefits of Secondary Compounds in Fleshy Fruits

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Because plants are rooted in place, their ability to colonize new areas often depends on animals, who consume fruits, move elsewhere, and then deposit the seeds contained in those fruits. This form of seed dispersal is essential for the natural regeneration of forests. To attract seed dispersers, plants produce nutritious and colorful fruits; however, the nutrients in those fruits can also attract fruit pests, such as insects and fungi that cause fruits to rot. As a defense against such enemies, plants produce an array of chemical compounds, called natural products or secondary compounds, that can act as insecticides or fungicides. These compounds are often used by humans as organic pesticides or in the treatment of infections, but very little is known about the variety of compounds produced in fruits and how they affect the animals that depend on fruits for food. This research will examine a group of these fruit natural products, the amide-alkaloids, that are found in tropical pepper plants (family Piperaceae), a large group that includes several economically important species (such as Piper nigrum, the fruits of which are the source of black pepper). A series of experiments will test the effects of individual amide-alkaloids on the organisms that consume pepper fruits in tropical forests. These organisms include fruit-feeding bats, which are the main beneficial seed dispersers of pepper fruits, as well as fruit pests such as insects and fungi. All field experiments will be conducted at the La Selva Biological Station in Costa Rica, an area where pepper plants and their associated fruit-feeding bats, insect pests and fungi are found in high abundance.The benefits of the study include an improved understanding of seed dispersal and the natural defense of fruits against pests -- two processes that are critical for plant survival and have direct relevance for agriculture and forest management. In addition, this study will create excellent opportunities for undergraduate and graduate student training due to its integrative approach that combines biology and chemistry. The research team will include students from both the US and Costa Rica, providing opportunities for international collaboration and cultural exchange. The results will be disseminated through scientific publications, as well as educational activities for K-12 students and the general public.