Electronic Theses and Dissertations

Date of Award

1-1-2020

Document Type

Thesis

Degree Name

M.S. in Biological Science

First Advisor

William J Resetarits

Second Advisor

Peter Zee

Third Advisor

Clifford Ochs

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

The reproductive success of many aquatic insects is highly dependent on where they deposit their eggs. Not all habitats are created equal. Some are more favorable than others for larval development. Therefore it would be evolutionarily advantageous for an ovipositing female to differentiate between them and choose the most suitable for her offspring’s survival. Numerous studies have shown that many species with complex life-cycles representing a diverse array of taxonomic groups sort themselves non-randomly among habitat patches on the basis of perceived habitat quality. In the case of dragonflies, insufficient evidence exists to support the hypothesis that this group can assess relevant indicators of patch quality and use those cues to select habitat. I conducted a series of experiments to investigate what effects a predatory fish, the green sunfish (Lepomis cyanellus), had on larval dragonfly performance and development and adult female habitat selection behavior. Developmental studies were performed to determine the degree of consumptive and non-consumptive effects of L. cyanellus and how they affect survival and other fitness correlates of larval dragonflies. I found that larval survival is significantly affected by the presence of uncaged L. cyanellus, but not affected by caged L. cyanellus. Caged L. cyanellus did not have an effect on fitness correlates, suggesting larvae are not capable of detecting fish. I examined whether female dragonflies actively avoid ovipositing in sites containing predatory fish which potentially inflict significant fitness costs via offspring predation. Results indicated that female adults of three common species of dragonflies did not discern between habitat patches based on the presence or absence of fish predators. This suggests that members of this group either rely on a bet-hedging or risk-spreading strategy, utilize a form of philopatry, or the presence of fish predators may not be an important factor for odonates in oviposition site selection. There is a mismatch between the results of the oviposition and development experiments, suggesting there is much more to learn about how dragonflies select habitat for their offspring, how their decisions affect aquatic community assembly, and how these can be used to inform conservation efforts designed to protect threatened odonate species.

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