Chemical defense of toad tadpoles under risk by four predator species

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  • Bálint Üveges
    Lendület Centre for Agricultural Research, BudapestKonrad Lorenz Institute of Ethology
  • Márk Szederkényi
    Konrad Lorenz Institute of Ethology
  • Katharina Mahr
    University of Debrecen
  • Ágnes M Móricz
    Lendület Centre for Agricultural Research, Budapest
  • Dániel Krüzselyi
    Lendület Centre for Agricultural Research, Budapest
  • Veronika Bókony
    Lendület Centre for Agricultural Research, Budapest
  • Herbert Hoi
    Konrad Lorenz Institute of Ethology
  • Attila Hettyey
    Lendület Centre for Agricultural Research, Budapest

Many organisms use inducible defenses as protection against predators. In animals, inducible defenses may manifest as changes in behavior, morphology, physiology, or life history, and prey species can adjust their defensive responses based on the dangerousness of predators. Analogously, prey may also change the composition and quantity of defensive chemicals when they coexist with different predators, but such predator-induced plasticity in chemical defenses remains elusive in vertebrates. In this study, we investigated whether tadpoles of the common toad (Bufo bufo) adjust their chemical defenses to predation risk in general and specifically to the presence of different predator species; furthermore, we assessed the adaptive value of the induced defense. We reared tadpoles in the presence or absence of one of four caged predator species in a mesocosm experiment, analyzed the composition and quantity of their bufadienolide toxins, and exposed them to free-ranging predators. We found that toad tadpoles did not respond to predation risk by upregulating their bufadienolide synthesis. Fishes and newts consumed only a small percentage of toad tadpoles, suggesting that bufadienolides provided protection against vertebrate predators, irrespective of the rearing environment. Backswimmers consumed toad tadpoles regardless of treatment. Dragonfly larvae were the most voracious predators and consumed more predator-naïve toad tadpoles than tadpoles raised in the presence of dragonfly cues. These results suggest that tadpoles in our experiment had high enough toxin levels for an effective defense against vertebrate predators even in the absence of predator cues. The lack of predator-induced phenotypic plasticity in bufadienolide synthesis may be due to local adaptation for constantly high chemical defense against fishes in the study population and/or due to the high density of conspecifics.

Original languageEnglish
Pages (from-to)6287-6299
Number of pages13
JournalEcology and Evolution
Volume9
Issue number11
Early online date19 Apr 2019
DOIs
Publication statusPublished - 1 Jun 2019
Externally publishedYes
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