The evolution of targeted cannibalism and cannibal-induced defenses in invasive populations of cane toads

Jayna L. DeVore, Michael R. Crossland, Richard Shine, Simon Ducatez

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Biotic conflict can create evolutionary arms races, in which innovation in one group increases selective pressure on another, such that organisms must constantly adapt to maintain the same level of fitness. In some cases, this process is driven by conflict among members of the same species. Intraspecific conflict can be an especially important selective force in high-density invasive populations, which may favor the evolution of strategies for outcompeting or eliminating conspecifics. Cannibalism is one such strategy; by killing and consuming their intraspecific competitors, cannibals enhance their own performance. Cannibalistic behaviors may therefore be favored in invasive populations. Here, we show that cane toad tadpoles (Rhinella marina) from invasive Australian populations have evolved an increased propensity to cannibalize younger conspecifics as well as a unique adaptation to cannibalism-a strong attraction to vulnerable hatchlings-that is absent in the native range. In response, vulnerable conspecifics from invasive populations have evolved both stronger constitutive defenses and greater cannibal-induced plastic responses than their native range counterparts (i.e., rapid prefeeding development and inducible developmental acceleration). These inducible defenses are costly, incurring performance reductions during the subsequent life stage, explaining why plasticity is limited in native populations where hatchlings are not targeted by cannibalistic tadpoles. These results demonstrate the importance of intraspecific conflict in driving rapid evolution, highlight how plasticity can facilitate adaptation following shifts in selective pressure, and show that evolutionary processes can produce mechanisms that regulate invasive populations.

    Original languageEnglish
    Article numbere2100765118
    Pages (from-to)1-8
    Number of pages8
    Journal Proceedings of the National Academy of Sciences of the United States of America
    Volume118
    Issue number35
    DOIs
    Publication statusPublished - 31 Aug 2021

    Keywords

    • Baldwin effects
    • Canalization
    • Co-adaptation
    • Phenotypic plasticity
    • Plasticity costs

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