The Effects of Landscape Structure on Pollination and Gene Flow in a Tropical Tree SpeciesEPA Grant Number: FP917245
Title: The Effects of Landscape Structure on Pollination and Gene Flow in a Tropical Tree Species
Investigators: Thompson, Pamela G
Institution: University of California - Los Angeles
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Terrestrial Systems Animal Ecology
People living in tropical forests are often dependent on ecosystem services provided by the forest, such as animal pollination of plants. These services can be disrupted by forest fragmentation. My research will examine the impact of landscape structure on pollination by comparing pollen-mediated gene flow in a bat-pollinated tree species, and pollinator abundance and diversity, between fragmented forest sites and continuous forest sites in Mexico.
Tropical dry forests are highly threatened due to human conversion of the landscape. These seasonal forests are also home to many endemic species and critical ecosystem processes. I am investigating how forest fragmentation in these areas may affect species interactions, specifically pollination of tropical trees by bats. I will compare continuous and fragmented forest sites, and examine nectar-bat abundance and diversity, as well as genetic patterns of pollen movement in a bat-pollinated tree.
I am using a landscape genetics and ecological approach to answer my questions about the impacts of forest fragmentation on bat-pollination. The first step is to locate and map the focal tree species (Crescentia alata), and collect leaf samples and seeds from these trees. By extracting DNA and genotyping the individual trees and their offspring (seeds) using neutral genetic markers, the spatial connectedness via pollen flow between the trees can be deduced, and patterns of pollen movement between trees in different sites (fragmented or not) can be compared. Additional work will focus on the pollinator abundance and diversity in the different sites, which will be accomplished through temporary capture of bats near flowering trees in the different sites, using mist-nets.
It is unclear whether nectar-feeding bats are directly impacted by forest fragmentation, or whether they can cope with these changes to the environment due to their ability to fly long distances. The degree of this impact may be different for different species of nectar-feeding bats. By comparing species and abundances of nectar-feeding bats in fragmented versus continuous forest sites, it is possible to see if there are any direct impacts to the bat pollinator community. By comparing pollen movement between sites, we can see an indirect genetic signature of the bat movement, and how this movement is impacted by changes to the landscape structure. We can also tell how connected different sites are, and the scale at which bats are moving pollen across the landscape.
Potential to Further Environmental/Human Health Protection:
This research will contribute to a larger understanding of the responses of an important tropical plant-animal interaction to the surrounding landscape structure, and how landscape features affect genetic connectivity among tropical trees. Knowledge of how bat pollinators use landscapes is essential for the design of successful conservation programs to preserve tropical ecosystem services. Moreover, by demonstrating the ecosystem service that bats perform by pollinating culturally important plants, this research can motivate decision-makers to protect threatened bat species such as Musonycteris harrisoni and Leptonycteris yerbabuenae. In addition, this project focuses on tropical dry forests which, although critically threatened due to a long history of human use and susceptibility to fire, are understudied compared to tropical rain forests. Only approximately 19 percent of Mexico’s original tropical dry forest remains today, and deforestation continues at a rate of 1.4 percent per year. An analysis of the ecosystem services provided by tropical dry forests in the Jalisco region of Mexico stated pollination by native bee pollinators and bats was one of the most essential services. Plants in the tropical dry forests are also more dependent on bats as pollinators than plants in the wet tropical forests, making this research highly valuable to the preservation of this critically threatened ecosystem.