Anti-predator Behaviors (Swarming)

Because evolution in Avida is completely open-ended and unsupervised, prey evolve a diverse array of behaviors in response to predation pressures. One of the most visible of these is grouping in the form of herds (or ‘swarms’). Provided that there are no food-resource restrictions putting pressure on prey to avoid each other, grouping behaviors evolve quite readily. Accordingly, we are currently looking to differentiate the factors that promote the evolution of these strategies (i.e. the dilution effect) from the factors that simply reinforce them once grouping has already evolved.

While looking at the videos below, keep in mind that we never introduce predators into these systems: predation and all other behaviors, evolve strictly via natural selection from a single prey ancestor. Moreover, we never artificially select for prey to form groups…prey herding evolves purely as a response to predation pressures.

[cvg-video videoId=’52’ width=’400′ height=’300′ mode=’playlist’ /]
Prey (blue, with juveniles in brown) quickly evolve to stay in groups when co-evolving with predators (red), but not when no predators are in the ecosystem. Organisms can occupy the same space (i.e. pass ‘over’ each other). In the above population, the predators clearly evolved to rapidly target and attack prey straying from the groups.

[cvg-video videoId=’51’ width=’400′ height=’300′ mode=’playlist’ /]