Evolution of swarming behavior is shaped by how predators attack

TL;DR

This study uses an evolutionary model to demonstrate that predator attack strategies critically influence the evolution of grouping behaviors like the selfish herd, confirming and refining Hamilton's domain of danger concept.

Contribution

The paper shows how predator attack modes affect the evolution of selfish herd behavior and extends Hamilton's domain of danger to density-dependent predation in a digital model.

Findings

Predator attack mode influences prey grouping evolution.

Density-dependent predation generalizes Hamilton's domain of danger.

Selfish herd behavior evolves under density-dependent predation.

Abstract

Animal grouping behaviors have been widely studied due to their implications for understanding social intelligence, collective cognition, and potential applications in engineering, artificial intelligence, and robotics. An important biological aspect of these studies is discerning which selection pressures favor the evolution of grouping behavior. In the past decade, researchers have begun using evolutionary computation to study the evolutionary effects of these selection pressures in predator-prey models. The selfish herd hypothesis states that concentrated groups arise because prey selfishly attempt to place their conspecifics between themselves and the predator, thus causing an endless cycle of movement toward the center of the group. Using an evolutionary model of a predator-prey system, we show that how predators attack is critical to the evolution of the selfish herd. Following this discovery, we show that density-dependent predation provides an abstraction of Hamilton's original formulation of ``domains of danger.'' Finally, we verify that density-dependent predation provides a sufficient selective advantage for prey to evolve the selfish herd in response to predation by coevolving predators. Thus, our work corroborates Hamilton's selfish herd hypothesis in a digital evolutionary model, refines the assumptions of the selfish herd hypothesis, and generalizes the domain of danger concept to density-dependent predation.