Independent Evolutionary Origins of Tetrodotoxin Resistance as a Test of the Geographic Mosaic of Coevolution

Utah State University, Logan UT

Investigators

Abstract

Evidence 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 neurotoxin tetrodotoxin (TTX), which blocks sodium channels in nerves and muscles. No known predator can ingest TTX and survive except for garter snakes of the genus Thamnophis. Previous work demonstrated that predator and prey have matched levels of defensive and exploitative abilities, but the source of newt toxicity is still unknown. High Performance Liquid Chromatography (HPLC) will be used to assay levels of toxin in laboratory bred and reared newts to determine whether the requisite individual, genetic and population variation exists for newts to evolve in response to predators, allowing an evaluation of 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 interaction, there are strong theoretical and empirical reasons to suspect that predator-prey interactions might be different. This research will shed important light on natural variation in an important neurotoxin, TTX, which is used widely in studies of nerve function and development, by identifying the sources of TTX in amphibians.