Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Among-species variation in the morphological responses of larval amphibians to native and invasive species.

Abstract

Amphibian larvae are common prey to various types of predators, according to the type of aquatic system they develop in. When they detect water-borne chemical cues from predators (kairomones), amphibian larvae often produce inducible defenses. An important component of such defenses is the alteration of the shape of the larvae, which often consists in producing rounder bodies, shorter tails and deeper tail fins in the presence of predators. However, the activation of these inducible defenses critically depends on the accurate recognition of predator cues. In that context, the human introduction of alien predators with whom local prey species have not shared a joint evolutionary history may pose a grave threat in part because the native prey may fail to recognize the cues of the novel predators and hence fail to trigger the corresponding antipredator phenotype. In this study we analyze the morphological responses of larvae of four amphibian species to two different types of predators: native dragonfly larvae and introduced red-swamp crayfish. We find that three out of the four species readily respond altering their morphology to the presence of dragonflies, but they all fail to respond to introduced crayfish. Moreover, the effect size of the morphological response seems to be congruent with the duration of the larval period of each species so that faster developing species show lesser responses to dragonflies whereas slower developing species show greater responses to them. This is congruent with faster developing species occupying temporary or even ephemeral ponds which typically have lower predator abundance.