DISSERTATION RESEARCH: The influence of landscape heterogeneity and mycorrhizal fungi on the distribution of an epiphytic orchid and its genetic variation

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

Deforestation threatens biodiversity in the tropics, not only by reducing the amount of forest, but also by dividing the forest that remains into small, isolated patches that species may not be able to reach or where species may not be able to survive once they get there. Epiphytes, plants that live atop other plants instead of on the ground, are a major part of the biodiversity in many species-rich tropical forests, and many of these epiphytes are orchids. Orchids have tiny seeds that wind can move over long distances, so they might be able to travel from one patch of forest to another. However, the tiny seeds cannot grow without the aid of specialized fungi,known as mycorrhizal fungi,that provide the orchids with nutrients. If the fungi are missing from a forest patch, the orchids will not survive once they get there. This research will test whether it is the dispersal of the seeds or the absence of the fungi that keeps orchids from growing in patches cut from tropical forest. Work will focus on Epidendrum firmum, an orchid found in the heavily used, mid-elevation forests of Costa Rica, and use a combination of molecular genetics in the U.S. and field experiments in Costa Rica. Because tropical epiphytes are among the most globally threatened groups of species, this research has practical value for conservation of natural resources. The work should provide valuable insights into the special ways in which dividing tropical forests into smaller patches can affect the many orchids that grow on tropical trees, whether by causing seeds to fall short or by disrupting the special ecological relationships upon which the orchids depend. The results should help guide efforts to conserve and restore the diversity of species in tropical forests. Furthermore, the project will train graduate and undergraduate students in tropical field research and molecular biology, and strengthen international scientific collaboration.