Generalist vs. specialist: cognition and behavioral flexibility in Gambusia across habitats

Identifying associations between ecological strategy and cognitive and behavioral traits is essential in predicting species sensitivity or persistence in the face of environmental change. Ecological generalists with a larger niche breadth are expected to exhibit high levels of behavioral flexibility, whereas specialists are likely to show increased performance of cognitive traits directly related to specific ecological challenges. To explore how ecological niche breadth is associated with cognitive and behavioral traits, we compared risk-taking, motivation, activity, and inhibitory control between two sister species of Gambusia that differ in ecological strategy: Gambusia affinis is an ecological generalist occupying a wide range of habitat types, and Gambusia geiseri is a specialist. Using a detour task and behavioral tracking, we evaluated cognitive and behavioral traits in both species from sympatric populations collected at two sites: one on the San Marcos River where G. geiseri dominates, and another on the Comal River characterized by more variable environmental conditions and roughly equal abundance of G. geiseri and G. affinis. We found that the generalist species, G. affinis was more likely to complete the detour task and was faster to exit a refuge indicating higher risk-taking behavior in this species. Gambusia geiseri from the variable habitat showed reduced solving success and slower solving speed which suggests that inhibitory control is associated with species identity and ecological niche breadth. Activity levels differed significantly across species and habitat type. We found a species by population interaction where G. affinis had a higher swimming velocity than G. geiseri in the Comal River, but a lower swimming velocity than G. geiseri in San Marcos River. Our findings highlight how cognitive and behavioral traits differ between generalist and specialist strategies and underscore these associations as drivers of species resilience to environmental change.