Date of Award

12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Entomology

First Advisor

Jeffrey D. Holland

Committee Chair

Jeffrey D. Holland

Committee Member 1

John B. Dunning

Committee Member 2

Ian Kaplan

Committee Member 3

Christian Krupke

Abstract

Habitat fragmentation and loss are principal factors that contribute to the decline of biodiversity which in turn has a negative impact on ecosystem function. There has been growing interest in understanding diversity’s role in the mechanisms behind ecosystem resilience with much attention focusing on how functional diversity, or the range of species’ ecological roles in a community, impacts ecosystem function. Under the functional insurance hypothesis, stability in ecosystems is maintained by species that perform similar functions but have asynchronous responses to disturbance. There are three proposed stability mechanisms that operate through species’ asynchronous responses: cross-scale resilience, response diversity, and density compensation. My objective in this study was to examine change in functional diversity resulting from habitat fragmentation and detect ecological stability mechanisms in a multitrophic community consisting of longhorned beetles and their beetle predators. I also considered predator-prey interactions between beetles and their insectivore avian predators at the community level.

To meet my objectives, I developed new functional traits to further capture beetle species’ functional roles and new methodology for examining change in functional diversity across trophic levels. I also expanded methodology to better detect one ecological stability mechanism, cross-scale resilience. Here, cross-scale resilience was operating if species with similar function also had different landscape response trends. I also determined a new way to assess predator-prey interactions in a multitrophic community with the use of avian visual perception of beetle prey visual contrasts. This approach allowed me to directly examine changes in avian predator and beetle prey abundance.

I found that prey functional diversity was more negatively impacted than predator functional diversity by habitat fragmentation. I detected two ecological stability mechanisms, cross-scale resilience and response diversity, which may have provided the beetle community greater resilience to habitat fragmentation. With respect to the interactions between avian predators and beetle prey, variations in visual contrasts of beetles moderated the degree to which abundance of birds in some functional groups impacted beetle abundance. Also a “functional link” may also be important for providing a greater resolution between the relationships between predator and prey abundance. I suggest that future studies investigate how vision-mediated predator-prey interactions may simultaneously impact the functional diversity of these trophic levels. In addition, assessing three-dimensional surfaces of functional diversity could reveal best landscapes for promoting functional diversity of ecosystem service providers in local landscapes.

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