Predator-induced morphological and chemical defenses in newt (Notophthalmus v. viridescens) larvae

Background/Question/Methods

Predator-induced phenotypic plasticity is characterized by modified traits that increase survivability when exposed to predators.  These traits occur during different life stages and are exhibited in an array of organisms.  Morphological plasticity is well documented in amphibians; however, predator-induced chemical defenses have received relatively little attention. The eastern red-spotted newt (Notophthalmus v. viridescens) is most vulnerable to predation during its larval stage. We assessed whether exposing eastern red-spotted newt larvae to predator scent cues would elicit morphological and chemical defenses. 

Results/Conclusions

Larvae exhibited morphological changes when exposed to predator scent cues, resulting in significantly decreased head widths and increased tail depths. Tail length, tail area, body length, and SVL (snout-vent-length) did not change significantly. Toxin concentrations showed no signs of being predator-induced.  However, it is possible that changes in chemical defenses could be detected at a later point in development. Further investigation of predator-induced phenotypic plasticity, especially on plasticity of chemical defenses, warrants more attention as these outcomes of species interactions remain unclear.