Dissertation Research: Neighborhood Effects on Seed Dispersal of a Neotropical Mistletoe

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Fruiting plants that rely on frugivorous birds for seed dispersal may experience important fitness consequences resulting from neighborhood influences on bird foraging movements. Birds respond to spatial patterns of fruit resource availability; thus these patterns will influence seed deposition patterns. Neighborhood effects on seed dispersal have not been studied. This research examines these effects on a tropical mistletoe species in pasture trees at Monteverde, Costa Rica. Neighborhood effects from the individual plant perspective, on three stages of dispersal; bird visitation, behavior during visits, and post- visitation movements, using an array of high and low density host and mistletoe neighborhoods (ca. 1 ha) will be determined. Mistletoes provide good systems for examining seed dispersal because bird deposition of seeds can be observed directly, and, as parasites, they have unique dispersal requirements. The study system provides a unique opportunity to examine these effects because of the arrangement of hosts and mistletoes at the site. The study will also enhance general knowledge of these little-studied tropical species. Disturbed habitats, such as the proposed site, are of increasing importance in the neotropics with the continuing loss of forests, and an understanding of ecological interactions in these habitats is likewise of increasing importance. Mistletoes can be serious pests in deforested areas where mostly susceptible trees are left standing; thus, this study is of both basic and applied interest.