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Date of Award

Spring 2011

Author's School

College of Arts & Sciences

Author's Department/Program

Biology

Abstract

Invasive exotic species have destructive effects on the ecology of their invasive range, as well as bring about tremendous economical loss. There has been much study on the mechanisms by which exotic species become successfully established. One important question is: How do exotic species successfully reproduce in their introduced range? Previous work has focused on particular traits that promote lower barriers to successful reproduction, such as autogamy or wind pollination. In entomophilous (insect-pollinated) species, those plants that are pollinated by generalist pollinators with wide diet breadths are predicted to be more successfully integrated into the native plant-pollinator network. After initial establishment, exotic plants may also accumulate pollinator species through time. This study asks: (1) Do exotic plants receive lower visitation rates or lower diversity of pollinator species than their native relatives? (2) Are exotic plants visited by relatively greater richness of generalist pollinators compared to native plants? (3) Do exotic plants accumulate specialist pollinators through time? In a field comparison of ten native and exotic species in the Fabaceae family that controlled for phylogeny, floral morphology, and environment, I found no significant difference in pollinator species diversity and visitation rate to native and exotic plants. However, I found that exotic plants on average received visits from pollinators with higher diet breadths than native plants, suggesting that exotic plant species are visited more by generalist pollinator species. Using a historic dataset, I examined the historic proportion of exotic to native plant visits of pollinator species and found that the focal exotic species were well-visited by pollinators since the late 1800s, and that more pollinators do not visited exotic species in the present study. My results support the hypothesis that exotic plants are visited more by generalist than specialist pollinators, but that these exotic plant species do not become more integrated and gain visits from specialist pollinators through time. With the high rate of native plant community invasion by exotic species, the results of this study may shed light on the possible integration trajectory of exotic species into native plantpollinator interaction networks.

Language

English (en)

Advisor/Committee Chair

Tiffany Knight

Second Advisor

Laura Burkle