Costs of exploiting poisonous prey: Evolutionary trade-offs in a predator-prey arms race

Abstract

Evolutionary trade-offs often are expected to arise between traits that share similar functions or resources. Such costs are well known from a variety of coevolutionary systems, but examples are conspicuously absent from predator-prey interactions. We present evidence of a trade-off between two disparate functions - predatory and antipredatory ability - in a species of garter snake that has evolved resistance to the neurotoxin of its prey. Patterns of among-family variation suggest a genetic basis to the trade-off. Both resistant and nonresistant populations of snakes exhibit the trade-off, suggesting that it stems from a fundamental aspect of organismal performance. This cost may help to explain the geographic mosaic of predator exploitative ability and prey defense that exists in this system.