Past and Present Risk: Exposure to Predator Chemical Cues Before and after Metamorphosis Influences Juvenile Wood Frog Behavior

摘要

Animals are exposed to different predators over their lifespan. This raises the question of whether exposure to predation risk in an early life stage affects the response to predators in subsequent life stages. In this study, we used wood frogs (Rana sylvatica) to test whether exposure to cues indicating predation risk from dragonfly larvae during the wood frog larval stage affected post-metamorphic activity level and avoidance of garter snake chemical cues. Dragonfly larvae prey upon wood frogs only during the larval stage, whereas garter snakes prey upon wood frogs during both the larval stage and the post-metamorphic stage. Exposure to predation risk from dragonflies during the larval stage caused post-metamorphic wood frog juveniles to have greater terrestrial activity than juvenile wood frogs that were not exposed to larval-stage predation risk from dragonflies. However, exposure to predation risk as larvae did not affect juvenile wood frog responses to chemical cues from garter snakes. Wood frogs exposed as larvae to predation risk from dragonfly larvae avoided garter snake chemical cues to the same extent as wood frog larvae not exposed to predation risk from dragonfly larvae. Our results demonstrate that while some general behaviors exhibit carry-over effects from earlier life stages, behavioral responses to predators may remain independent of conditions experienced in earlier life stages.