Collaborative Research: Patterns of Variation in Newt Tetrodotoxin Levels -- Evaluating the Potential for Predator-Prey Coevolution

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Brodie, III.9903829Evidence for arms race coevolution between predator and prey will be evaluated in a unique natural interaction between toxic newts and their resistant snake predators. Newts possess the potent neurotoxin tetrodotoxin (TTX), which blocks sodium channels in nerves and muscles. No known predator can ingest TTX and survive except for a single species of garter snake, Thamnophis sirtalis. Previous work has demonstrated that populations of this predator vary in their resistance to TTX, and that the potential to evolve increased resistance is present. To determine if newt defenses match patterns of predator exploitative ability as predicted by coevolutionary theory, High Performance Liquid Chromatography (HPLC) will be used to assay levels of toxin within and among populations of newts. This approach will determine if the requisite individual, genetic and population variation exists for newts to evolve in response to predators, and will also evaluate whether observed patterns of matching are consistent with an "arms race" view of coevolution.Understanding the interactions between species that drive coevolution is a major goal of evolutionary biology. Coevolution, in which one species evolves in response to another species, is thought to be one of the major engines of biodiversity. Although coevolution is thought to be a common outcome of many ecological interactions, there are strong theoretical and empirical reasons to suspect that predator-prey interaction may be different. The current study will represent one of the first and most complete studies of coevolution among predator and prey. Additionally, this research will shed important light on natural variation in TTX, an important neurotoxin used widely in studies of nerve function and development, by identifying the sources of TTX in prey and the mechanism of TTX resistance in predators.