Simulation game answers evolutionary questions
New research into observing interactions between schools of fish and predators has taken a unique approach – a video game! Researchers used simulated prey to document group formation and movement between real and simulated animals.
In a paper published in Science, the researchers report some of the strongest evidence that collective motion in animal groups, such as schools of fish, can evolve as a finely tuned defence mechanism against an attack from predators. This has been suggested by other research, but the many variables that can drive group movement have made it difficult to observe a direct link to self defence.
The study, conducted at Princeton University, projected simulated prey – which appeared as small reddish dots - onto one side of a tank containing the ravenous bluegill sunfish. The prey interacted spontaneously with one another based on encoded behaviour traits, and the researchers documented in the prey the resulting individual behaviours and group formations. Ultimately, the bluegills were most likely to avoid attacking simulated prey that had formed co-ordinated and mobile groups.
These results show that group formation itself can deter a predator, even if the prey are completely unaware of the danger, much like the simulation. This suggests that the specific configuration of animal groups is an evolved defence. The ideal configurations exhibited by the simulated prey mirror those of many animal groups, whereby individuals follow cues to co-ordinate collective movement.
Large groups that did not move much eventually fell victim to attacks in 'high-risk' areas of the projected space in which bluegills attacked. Yet when groups of prey moved with co-ordination, they passed through these high-risk areas too quickly for each individual bluegill to make its attack.
Professor Couzin of Princeton University said: "Effectively, the bluegills were playing an immersive video game in which they hunted. By evolving the prey groupings, the game becomes harder and harder for the predators, as when a video game adapts to the strategy employed by the players. In a similar way, our prey 'evolved' to the mode of hunting that the bluegills exhibited, adapting better strategies that allowed them to evade hunting more effectively."
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