How local antipredator response unbalances the rock-paper-scissors model

TL;DR

This study investigates how local antipredator responses in a rock-paper-scissors predator-prey system can disrupt species coexistence, leading to spatial domain formation and threatening biodiversity, especially with high organism mobility.

Contribution

It introduces a spatial stochastic model incorporating local antipredator strategies and demonstrates their impact on species dominance and biodiversity in cyclic predator-prey interactions.

Findings

Local antipredator responses create spatial domains dominated by single species.

Reducing predation probability locally prevents a species from dominating.

High mobility exacerbates the threat to biodiversity caused by local unbalancing.

Abstract

Antipredator behaviour is a self-preservation strategy present in many biological systems, where individuals join the effort in a collective reaction to avoid being caught by an approaching predator. We study a nonhierarchical tritrophic system, whose predator-prey interactions are described by the rock-paper-scissors game rules. We performed a set of spatial stochastic simulations where organisms of one out of the species can resist predation in a collective strategy. The drop in predation capacity is local, which means that each predator faces a particular opposition depending on the prey group size surrounding it. Considering that the interference in a predator action depends on the prey's physical and cognitive ability, we explore the role of a conditioning factor that indicates the fraction of the species apt to perform the antipredator strategy. Because of the local unbalancing of the cyclic predator-prey interactions, departed spatial domains mainly occupied by a single species emerge. Unlike the rock-paper-scissors model with a weak species because a nonlocal reason, our findings show that if the predation probability of one species is reduced because individuals face local antipredator response, the species does not predominate. Instead, the local unbalancing of the rock-paper-scissors model results in the prevalence of the weak species' prey. Finally, the outcomes show that local unevenness may jeopardise biodiversity, with the coexistence being more threatened for high mobility.