DISSERTATION RESEARCH: Linking mechanism to pattern in community assembly: ant-mediated seed dispersal in tropical pioneer trees

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A central goal of ecology is to understand why species live where they do. We already know that different species have different requirements to survive, grow, and reproduce. For example, some trees can thrive in the shade whereas others need lots of sunlight. These light-loving trees are called "pioneer" species because they are usually the first to colonize open areas after a disturbance topples large trees that once grew there. How do their seeds get there? Either they are dispersed after an area becomes sunny or they are dispersed much earlier, become buried in the soil, and "wait" for trees above them to die. In both cases, plants often rely on animals to move their seeds. Ants are one of the most important seed dispersers because they both move seeds and "plant" them in the soil. Most of what scientists know about seed dispersal by ants comes from studies investigating seeds that provide a food reward for the ants. However, most plant seeds, including those of most commercially important crops, do not provide a food reward for ants. The scientists doing this study have discovered that ants may move these types of seeds, despite the lack of a reward. They think that ants are chemically "tricked" to carry seeds that smell good but can't be eaten. The goal of this project is to test this idea and figure out what the good-smelling chemicals may be. Results will help land managers understand how plants move into new places, which is an important process in forest restoration. This research will use a tropical tree species and a common, ground-dwelling ant to determine possible chemical cues that promote seed dispersal. The approach includes fractioning, identifying, synthesizing, and field-testing seed extracts to identify which chemicals attract ants. Seed extracts will be tested both in tropical and temperate environments to help determine which species engage in ant-mediated seed dispersal. The results will help guide strategies for plant conservation, restoration, and invasive species management. In addition, a graduate student will be mentored in laboratory techniques and field research.