ABS 2022
Predation intensity drives evolution of cognition independently of brain size in a Trinidad killifish
Meghan N. Korte, Matthew R. Walsh. University of Texas at Arlington, Arlington, TX, United States

Vertebrates exhibit extensive variation in brain size in which larger brains are linked with enhanced cognition and survival. Therefore, natural selection may favor a connection between brain size and shifts in cognition and behavior. Yet, most research has focused on comparisons across species; experimental tests of the ecological drivers of this variation are lacking. Trinidadian killifish are found in sites that differ in predation intensity: fish in sites with predators experience high extrinsic mortality while fish in sites that lack predators experience high competition. Such decreases in predation are linked with the evolution of a larger brain. Here we tested the link between brain size and shifts in cognition via associative learning tasks and behavioral assays. Predation level significantly impacted cognitive-behavioral profiles of fish. Fish from sites without predators were faster learners and better problem-solvers, however we did not find interactions between predation and brain size for cognitive traits. This indicates cognition evolved as a function of predation and provides experimental evidence that cognition may evolve independently of brain size.