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Eavesdropping on the enemy: The importance of chemical cues for inducible defenses

Schoeppner, Nancy Marie (2006) Eavesdropping on the enemy: The importance of chemical cues for inducible defenses. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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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.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Schoeppner, Nancy Marienschoepp@pitt.eduNSCHOEPP
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairRelyea, Rickrelyea@pitt.eduRELYEA
Committee MemberTurner,
Committee MemberHatfull, Grahamgfh@pitt.eduGFH
Committee MemberTonson, Stephentonsor@pitt.eduTONSOR
Committee MemberCarson, Walterwalt@pitt.eduWALT
Date: 21 June 2006
Date Type: Completion
Defense Date: 6 April 2006
Approval Date: 21 June 2006
Submission Date: 11 April 2006
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: alarm cues; chemical cues; kairomones; larval amphibians; inducible defenses; phenotypic plasticity
Other ID:, etd-04112006-150249
Date Deposited: 10 Nov 2011 19:35
Last Modified: 15 Nov 2016 13:39


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