Genetic heterogeneity alleviates behavioral trade-off between exploration and vigilance in Drosophila

Behavioral trade-offs are a major constraint on animal performance, but group living can reshape such constraints. Using genetically distinct strains of Drosophila melanogaster, we examined how aggregation and heterogeneity shape the exploration-vigilance trade-off under predator-like looming stimuli. A latent negative relationship between exploration and vigilance became apparent when aggregated, suggesting improved behavioral performance compared to solitary condition. Heterogeneity within the group further enhanced performance beyond expected levels, indicating an alleviation of the cost of balancing exploration and vigilance. We then applied a phenome-wide higher level association study (PheHAS) to identify phenotypic features associated with this alleviation across strain pairs. Differences in activity patterns, together with similarity in infection-response traits, were linked to greater trade-off alleviation. These results indicate that aggregation and heterogeneity have distinct effects on group behavior and provide a general framework for linking phenotypic diversity to collective performance.