Prey defence phenotype mediates multiple‐predator effects in tri‐trophic food webs

Abstract

1. The emphasis on mechanisms governing the interaction among predators (e.g. cooperation, competition or intraguild predation) has driven the understanding of multiple-predator effects on prey survival and dynamics. However, overwhelming evidence shows that prey can adaptively respond to predators, exhibiting multiple defensive phenotypes to cope with predation. Nevertheless, there is still a relatively scarce theory connecting the emergence of prey defences in complex multi-predator scenarios and their ecological consequences.2. Using a mathematical approach, we evaluated the prevalence of defended prey phenotypes as a function of predator-induced mortality in a two-predator system, and how prey and phenotype dynamics affect trophic cascades. We also evaluated such responses when prey manifests a general defence against both predators (i.e. risk reducing) or a specialized defence against one predator at the expense of defence against the other predator (i.e. risk trade-off), and when such phenotypes induce fitness and foraging costs.3. We showed that the emergence of defended phenotypes under multiple predators depends on predator-induced mortality rates, the magnitude of phenotype costs and the effect of the defensive phenotype on the performance of all predators. 4. Risk-reducing phenotypes enhance prioritized responses to predators with high killing rates, but prioritized responses are diminished when prey manifest risk trade-off phenotypes. Finally, we showed that resource abundance across the predation gradient directly depends on the prevalence of certain prey phenotypes and their effect on foraging costs. 5. Ultimately, our results depict the implications of prey defences on prey and basal resources abundance in a multiple predators' environment, highlighting the role of the identity of defensive strategies in mediating the strength and nature of trophic cascades, via consumptive or non-consumptive effects.

Reduced palatability, fast flight, and tails: Decoding the defence arsenal of Eudaminae skipper butterflies in a Neotropical locality

“…At the post-contact predation sequence, chemical defences producing unpalatability might successfully deter prey consumption and are frequently associated with visual cues that act as warning signals (i.e., aposematism). In nature, all anti-predator strategies are imperfect, as predators evolve counteracting mechanisms (e.g., tolerance to chemical defences; Fink & Brower, 1981) and all ecosystems contain multiple types of potential predators (Guariento et al, 2022). Thus, a major question in evolutionary ecology is how often anti-predator defences transition within lineages over evolutionary time (e.g., Loeffler-Henry et al, 2023), and which contexts favour single-defence specialization versus multiple anti-predator defences (e.g., McClure et al, 2019).…”