All ETDs from UAB

Advisory Committee Chair

James B McClintock

Advisory Committee Members

Ryan L Earley

Daniel A Warner

Document Type

Thesis

Date of Award

2016

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

Predator chemical cues have been widely demonstrated to influence developmental plasticity in aquatic prey. However, understanding the role that conspecifics have on an individual’s anti-predator response has received little attention. The present thesis investigated the developmental plasticity of individual and groups of the amphipod Hyalella azteca chronically exposed to kairomones from predatory sunfish. Previous field studies have suggested that small body size in H. azteca is a likely adaptive response to reducing predation by sunfish, but no experimental studies have been carried out to test if the amphipods have a developmental response to the presence of sunfish. Containers with single individuals or groups of three amphipods were chronically exposed to water containing sunfish kairomone or a control for 30 days. Grouped amphipods that were chronically exposed to sunfish kairomone had body lengths that were significantly shorter than grouped amphipods exposed to controls, while amphipods held individually, regardless of cue treatment, showed no significant difference in body length. Five days after the 30 day exposure (Day 35), all amphipods were acutely exposed to sunfish kairomone to test behavioral responses to structural refuge. Grouped amphipods sought refuge less often than solitary amphipods. At time points of 25 and 30 min, amphipods pre-exposed to kairomones sought refuge significantly more often than did amphipods with no prior exposure to the predator cue. To further test if the reduction in body size observed in grouped amphipods exposed to sunfish kairomone was related to a conspecific chemical cue, individual amphipods were placed in mesh-capped, opaque bottles and submerged in water within a container. Each container housed either three or no amphipods and received either kairomone or control water for 30 days. Amphipods exposed to kairomones in combination with conspecific cues grew to significantly smaller body lengths than did amphipods exposed to conspecific cues alone. These results mirrored the group vs individual exposure experiment described above, suggesting that a conspecific chemical cue is necessary to induce an anti-predator response. The present thesis demonstrates a group effect on the induction of developmental plasticity in a presumptive adaptive trait from a conspecific chemical cue in a prey species exposed to a predator scent.

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