Inducible defenses are traits that prey develop only in the presence of predators. These defenses can take the form of behavioral, morphological, chemical, or developmental changes and serve as flexible protection in variable environments. For larval amphibians in particular, the ability to respond to predators over the course of development can make a significant difference in survival. Our understanding of inducible defenses in larval anurans is particularly thorough, but we have considerably less information on the defenses of larval salamanders. In this study, we raised five species of larval Ambystoma salamanders in a common garden environment and manipulated the presence and absence of predator cues from larval dragonflies. During each 4-week experiment, we quantified behavior, life history, and morphology.
Results/Conclusions
We found that all species of larval salamanders responded to the predators. In terms of behavior, we found species-level variation. Larvae exposed to predator cues moved less and used refuges more than larvae exposed to no cues. Interestingly, the response to predators declined over time. Morphological analyses suggest that the largest shape differences occur in the width of the head, shape of the tail, and attachment point of the tail. These data suggest that, in general, Ambystoma salamanders respond to predation cues much in the same way anurans do. Future work will examine the predator-induced responses of many more Ambystoma species and this will allow us to begin examining phylogenetic patterns of inducible defenses.
