Alien versus predators: effective induced defenses of an invasive frog in response to native predators

Inducible defenses enhance fitness of prey living in environments with unpredictable predation risk, but these plastic reactions depend on the detection of the threat by the prey. To anuran larvae confronted with unknown predators, only prey‐borne cues are noticeable, generally triggering either an incomplete set of reactions or no response at all. Thus, we should expect a certain disadvantage for establishing invasive anurans if tadpoles are unable to recognize local predators. Here, we test the presence and effectiveness of inducible defenses in tadpoles of the invasive frog Discoglossus pictus confronting two native predators. Using both lab and mesocosm experiments, we also evaluate the effects these predators may exert on the invasive frog populations. Interestingly, although D. pictus has been introduced from another continent, its native (African) and invasive (European) ranges are included in the same ecoregion (Mediterranean Basin), sharing several genera and species of aquatic predators. In both experiments and using both invertebrates, tadpoles responded to the native predators, and our results match those usually reported in similar predator‐prey systems using combinations of native species. Moreover, these reactions seem clearly effective in reducing mortality and injury rates of D. pictus tadpoles. We believe that the introduced frog is highly benefiting from a previous knowledge of populations of these or similar predator species. Therefore, even though native and invasive ranges of D. pictus are in different continents, the similarity of predator communities of both areas may be advantageous for its establishment and expansion. We tested the presence and effectiveness of inducible defenses in tadpoles of the invasive frog Discoglossus pictus confronting two native predators, using both lab and mesocosm experiments. Although D. pictus has been introduced from another continent, tadpoles effectively responded to the native predators, and our results match those usually reported in similar native‐native predator‐prey systems. We believe that the introduced frog is benefiting from a previous knowledge of similar predator populations since its native (African) and invasive (European) ranges are included in the same ecoregion.