Term of Award

Spring 2010

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Stephen P. Vives

Committee Member 1

Edward B. Mondor

Committee Member 2

Daniel F. Gleason

Abstract

Olfaction in fishes can be an important mechanism in determining the level of predation risk. Many fishes possess alarm signaling systems, wherein an individual can detect injured conspecifics via olfaction and respond behaviorally to the presence of a predator. The superorder Ostariophysi exhibits a fright reaction to injured conspecifics, characterized by specialized cells and alarm substances. I tested if a live-bearing non-ostariophysan, Gambusia holbrooki, exhibited a similar behavioral response to its injured conspecifics. I also examined the effects of exposure to this and other predatory cues during a single pregnancy cycle. I hypothesized that immediate exposure to the cues would provoke a clear behavioral reaction, and long-term exposure would cause G. holbrooki to alter nutrient provisioning to developing embryos, resulting in altered offspring morphology and performance. Gambusia holbrooki exposed to skin extract (an alarm substance from injured conspecifics) schooled significantly closer than fish not exposed to skin extract. Mosquitofish did not display any discernible life-history plasticity in response to predatory cues during a single pregnancy. They did, however, exhibit marked differences in fecundity-mother size relationships between two locations in coastal Georgia. These results confirm the existence of a behavioral alarm reaction in G. holbrooki, and different reproductive traits between locations. Many animals experience morphological and life-history plasticity in response to shifts in abiotic and biotic environmental factors. Additional replication is necessary to determine if this species alters nutrient provisioning to embryos in response to predation risk.

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