Rapid evolution of coordinated and collective movement in response to artificial selection

Abstract

Collective motion occurs when individuals use social interaction rules to respond to the movements and positions of their neighbors. How readily these social decisions are shaped by selection remains unknown. Through artificial selection on fish (guppies, Poecilia reticulata) for increased group polarization, we demonstrate rapid evolution in how individuals use social interaction rules. Within only three generations, groups of polarization-selected females showed a 15% increase in polarization, coupled with increased cohesiveness, compared to fish from control lines. Although lines did not differ in their physical swimming ability or exploratory behavior, polarization-selected fish adopted faster speeds, particularly in social contexts, and showed stronger alignment and attraction responses to multiple neighbors. Our results reveal the social interaction rules that change when collective behavior evolves.

Coordination of movement via complementary interactions of leaders and followers in termite mating pairs

“…Laboratory experiments have shown that individual behaviour underlying group coordination can evolve in just a few generations [47,48]; however, such changes have yet to be documented in the field. Species invasions provide opportunities to observe evolutionary changes in behaviour [49,50].…”

Evolution of sociability by artificial selection *

“…Field observations, which were followed up by controlled laboratory studies, indicated that Trinidad guppies (Poecilia reticulata) from distinct populations that vary in predation risk show heritable variation in school size, with guppies from high predation pools having larger and more cohesive groups as well as higher survival rates when exposed to predators (Seghers 1974;Magurran et al 1992;O'Steen et al 2002;Huizinga et al 2009). Recently, Kotrschal et al (2020) artificially selected for three generations on guppies' group polarization, which is the tendency of school members to align with each other's directional movement. This led to significant increases in polarization and cohesiveness in females.…”

Optimal use of simplified social information in sequential decision-making

“…I argue that optimality should bridge the gap between information and behaviour. In social animals that are routinely exposed to the choices others make, responses to that information source will be subject to selection [25,26] and thus are likely to be optimized with respect to fitness. Agents who do not respond optimally to the available information should be out-competed by those who do, whether by evolved instinct or the capability to learn, depending on the life cycle of the species.…”