Coevolutionary patterns caused by prey selection

TL;DR

This paper investigates how prey selection influences coevolutionary dynamics between predators and prey, revealing that prey choice can lead to asymmetric patterns and episodic reversals, especially in small populations, impacting extinction risks.

Contribution

It introduces an analytical framework for predator-prey coevolution considering prey selection, highlighting its effects on coevolutionary patterns and stability, which were previously unexplored.

Findings

Prey selection causes asymmetric coevolutionary patterns in small populations.

In large populations, prey selection still results in known symmetrical patterns.

Prey selection drives phenotypes towards more extreme values, increasing extinction risk.

Abstract

Many theoretical models have been formulated to better understand the coevolutionary patterns that emerge from antagonistic interactions. These models usually assume that the attacks by the exploiters are random, so the effect of victim selection by exploiters on coevolutionary patterns remains unexplored. Here we analytically studied the payoff for predators and prey under coevolution assuming that every individual predator can attack only a small number of prey any given time, considering two scenarios: (i) predation occurs at random; (ii) predators select prey according to phenotype matching. We also develop an individual based model to verify the robustness of our analytical prediction. We show that both scenarios result in well known similar coevolutionary patterns if population sizes are sufficiently high: symmetrical coevolutionary branching and symmetrical coevolutionary cycling (Red Queen dynamics). However, for small population sizes, prey selection can cause unexpected coevolutionary patterns. One is the breaking of symmetry of the coevolutionary pattern, where the phenotypes evolve towards one of two evolutionarily stable patterns. As population size increases, the phenotypes oscillate between these two values in a novel form of Red Queen dynamics, the episodic reversal between the two stable patterns. Thus, prey selection causes prey phenotypes to evolve towards more extreme values, which reduces the fitness of both predators and prey, increasing the likelihood of extinction.