Exploring the evolution of a trade-off between vigilance and foraging in group-living organisms

TL;DR

This study uses a digital model to investigate how collective vigilance influences the evolution of group foraging in prey, highlighting the roles of relatedness and reproductive strategy in this process.

Contribution

It demonstrates that collective vigilance can promote gregarious foraging behavior in digital prey models, especially among highly related groups with semelparous reproduction, under no direct costs of grouping.

Findings

Collective vigilance suffices to select for group foraging without direct costs.

Highly related groups with semelparous reproduction are most likely to evolve gregarious foraging.

Grouping benefits are influenced by genetic relatedness and reproductive strategy.

Abstract

Despite the fact that grouping behavior has been actively studied for over a century, the relative importance of the numerous proposed fitness benefits of grouping remain unclear. We use a digital model of evolving prey under simulated predation to directly explore the evolution of gregarious foraging behavior according to one such benefit, the "many eyes" hypothesis. According to this hypothesis, collective vigilance allows prey in large groups to detect predators more efficiently by making alarm signals or behavioral cues to each other, thereby allowing individuals within the group to spend more time foraging. Here, we find that collective vigilance is sufficient to select for gregarious foraging behavior as long there is not a direct cost for grouping (e.g., competition for limited food resources), even when controlling for confounding factors such as the dilution effect. Further, we explore the role of the genetic relatedness and reproductive strategy of the prey, and find that highly related groups of prey with a semelparous reproductive strategy are the most likely to evolve gregarious foraging behavior mediated by the benefit of vigilance. These findings, combined with earlier studies with evolving digital organisms, further sharpen our understanding of the factors favoring grouping behavior.