Collective Motion as an Ultimate Effect in Crowded Selfish Herds

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Theoretical ecology

Background:

• The selfish herd hypothesis explains group formation in prey animals for individual fitness.
• Previous models overlooked how crowding affects individual adaptation within social groups.

Purpose of the Study:

• To simulate prey adaptation to predation within a crowded environment, considering restrained individual mobility.
• To investigate how individual competition influences collective behavior and group dynamics.

Main Methods:

• Developed an evolutionary model simulating agents on a lattice with restricted movement due to conspecifics.
• Implemented selection for behavioral traits that minimize predation risk within the simulated herd.
• Analyzed the emergent collective motion and group structure resulting from individual-level competition.

Main Results:

• Crowded environments led to cohesive herds being replaced by morphing, moving aggregates.
• Border agents actively shifted to share predation risk with inner herd members.
• Collective motion arose purely from selfish individual competition, independent of group benefits.

Conclusions:

• Incorporating crowding effects into the selfish herd model enhances outcome diversity.
• Individual-level selection can explain a broader range of collective animal behaviors.
• The study highlights the role of individual adaptation in shaping social dynamics under predation pressure.