Effects of environmental history, sibship, and age on predator-avoidance responses of tadpoles

Gray treefrog (Hyla chrysoscelis) tadpoles exhibit predator-avoidance behaviors, such as increased refugium use, in the presence of predators. We presented tadpoles with waterborne chemical cues from predators and with epidermal extracts of conspecifics. We also examined whether responses of tadpoles are affected by the presence of a predator in the environment in which they were reared, by their developmental stage, or by genetic (family) effects. Predator cues significantly increased the tadpoles' use of a refugium. Although there was no effect due to age alone, there was a significant interaction between predator cues and age, indicating that tadpoles may exhibit predator avoidance at most vulnerable sizes. The degree of expression of this behavior is also dependent upon the environmental history of the organism (i.e., rearing condition), indicating that this response can interact with environmental conditions (i.e., composition of the predator community). Additionally, we found no differences among full-sib families, suggesting that predator avoidance in this species may be influenced more by the environment than by genes.