Meeting Abstract
P1.29 Thursday, Jan. 3 Selection on Behavior Drives Evolution of Motor and Sensory Characters in Autonomous Fish-like Robots DOORLY, N*; STICKLES, E; SAHKTAH, H; ROSENBLUM, H; GUTIERREZ, A; MCARTHUR, G; LIEW, C; ROOT, R; LONG, J; Vassar College; Vassar College; Vassar College; Vassar College; Vassar College; Vassar College; Lafayette College; Lafayette College; Vassar College nidoorly@vassar.edu
Our aim was to test the hypothesis that selection for foraging efficiency and predator avoidance was important in early vertebrates. To this end, we designed and built a simple environment with a predatory robot pursuing a series of structurally-variable prey robots. All robots were fully autonomous and swam with a flapping tail. Using two light-sensitive eyes, prey robots foraged by moving up a light gradient and holding station in orbit around the source. Prey robots foraged until they detected the predator, at which point they initiated an escape routine. We allowed the prey to evolve the following characters: (1) the number of vertebrae, (2) the span of the caudal fin, and (3) the sensitivity of IR proximity detectors, which act as a proxy of the lateral line. In each generation of six prey, we applied a constant relative fitness criterion to individual performance, rewarding robots who swam quickly, kept far away from the predator, stayed close to the food source, attempted numerous escapes, and escaped with high acceleration. The three robots with the highest fitness in any generation were allowed to reproduce, with rank order determining individual contribution of gametes to the mating pool. Parental gametes were mutated and then combined randomly in a software-based genetic algorithm, creating six novel offspring genotypes. These genotypes were in turn used to fabricate new tails and to set new detection thresholds. After five generations of selection, the magnitude of all three characters increased. We tentatively conclude that selection for foraging efficiency and predator avoidance might have been a factor in the early evolution of the vertebral column, the caudal fin, and the lateral line.
