Many species rely on phenotypically plastic traits to defend themselves against predators and the induction of these phenotypes require reliable environmental cues. In aquatic systems, defensive phenotypes are induced by chemical cues emitted during predation events. Using larval amphibians as a model system, my dissertation focuses on how prey use the different types of chemical information available from predators (kairomones) and prey (alarm cues) and how prey integrate their defensive decisions in response to chemical cue variation over space and time.
Predation cues contain information on the identity of the predator (kairomones) and the identity of the attacked prey (alarm cues). I have shown that different alarm cues (from different predator diets) induce different magnitudes of prey defense and discovered that the magnitude of the response depends on the evolutionary divergence time between the diet and the responding prey. Because chemical cues from consumed prey induce different suites of traits than cues from starved predators or damaged prey, I have also performed experiments to determine the role the predators themselves play in producing the cue (i.e. releasing a kairomone or digesting alarm cues). I found that digestion of the prey is essential to induce the complete suite of defensive traits.
Because induced defenses have associated costs, prey should balance these costs and benefits by fine-tuning their responses to their environment over space and time. To do this, prey must be able to detect and respond to changes in risk when they move into new environments (spatially) or when predators come and go (temporally). I have found that tadpoles can detect small differences in risk, but that experiencing pulses of risk, when compared to a constant risk, largely does not alter their defensive decisions. Collectively, this work demonstrates the important role of environmental cues in understanding the ecology and evolution of inducible defenses.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04112006-150249 |
| Date | 21 June 2006 |
| Creators | Schoeppner, Nancy Marie |
| Contributors | Dr. Stephen Tonson, Dr. Graham Hatfull, Dr. Andrew Turner, Dr. Rick Relyea, Dr. Walter Carson |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-04112006-150249/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0318 seconds