Date of Award:

5-1-2003

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

Edmund D. Brodie Jr.

Committee

Edmund D. Brodie Jr.

Committee

Daryll B. DeWald

Committee

Stephan Bialkowski

Abstract

The Common Garter Snake (Thamnophis sirtalis) preys upon the Rough-skinned Newt (Taricha granulosa), which contains tetrodotoxin (TTX). I investigated how snakes consume potentially deadly newts and the consequences thereof. Individual snakes assess their resistance relative to newt toxicity and reject prey too toxic to consume. Behavioral moderation of toxin exposure provides the association between individual resistance and fitness necessary for the coevolution of lethal toxins and resistance. After newt consumption, snakes experience tremendous toxin loads. Because TTX is extremely toxic, present in large quantities in newts, and highly resistant snakes ingest multiple newts, snakes can harbor enough TTX in their liver to incapacitate or kill avian predators. Whether snake toxicity constitutes a chemical defense is unknown. However, the persistence of foreign toxins in an organism may be the necessary first step for evolution of the sequestration of toxin for consequent protection of that organism.

Included in

Biology Commons

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