Graduation Semester and Year

2015

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Quantitative Biology

Department

Biology

First Advisor

Paul Chippindale

Abstract

Intraguild Predation (IGP) is a form of interference competition characterized by an intraguild predator consuming interspecific competitors, the intraguild prey. This interaction is extremely common in nature, but mechanistic and descriptive models usually predict that it is unstable with either the IG prey or IG predator becoming locally extinct, dependent on initial conditions. Only intermediate shared prey availability leads to IGP stability in these models, and this condition is not common. In this work, I used dragonfly nymphs to examine behavioral and morphological aspects of consumptive competition and predator avoidance that may act to stabilize IGP, particularly in systems with more than two predators. There are two primary hypotheses in this treatment. The first is that prey capture is morphologically mediated and that this leads to differences in diet composition that can promote IGP stability by allowing prey specialization. The second is that there is a behavioral tradeoff that leads to disproportionate feeding on competitively superior IG prey by an IG predator that may lead to IGP stability. This tradeoff was hypothesized to exist in terms of direct prey capture as well as movement and space use patterns. Both of these mechanisms were found to exist, with species variation in mortality being explained by their behavior, in spite of morphological defenses compensating for the lack of behavioral defenses in some species. While effect of this possible mechanism on IGP stability was not directly examined, further long-term study should elucidate it.

Disciplines

Biology | Life Sciences

Comments

Degree granted by The University of Texas at Arlington

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