Exposure to predation risk reduces lateralization in fathead minnows

Lateralization of cognitive functions impacts many behaviours related to fitness and, in most species, varies greatly among individuals. Laboratory and field studies have suggested that within-species variation in lateralization is partly due to phenotypic plasticity. For example, in fish, prey that have experienced predation risk during early ontogeny develop highly lateralized phenotypes, and this lateralization often favours prey in evading predators. In contexts other than predation, plasticity of lateralization has also been reported for adult fish. Therefore, we asked whether adult fathead minnows, Pimephales promelas, exposed to high predation risk would also show plasticity linked to increase lateralization. We exposed minnows to conspecific alarm cues for up to 8 days to simulate predation risk and tested their lateralization with a standard detour test. The treatment affected lateralization but in an unexpected direction: Individuals exposed to high predation risk showed lower lateralization scores compared to control fish. In addition, fish within groups exposed to risk reduced the variability in their directionality of lateralization; that is, they showed a similar turning preference in the detour task. Our study suggests that lateralization can vary in response to predation risk in adult fish.