A conserved teleost motor asymmetry requires evolutionary retention of vision

Behavioral laterality is a prominent Bilateria feature, where motor functions are performed with a directional preference. Underlying such behaviors is thought to be hemispheric specializations that improve behavioral performance. Despite the prevalence, how behavioral lateralization is modulated throughout evolution is poorly understood. Comparative approaches are a powerful strategy for addressing fundamental biological questions from individual to evolutionary scales. Previously, we described a robust visuomotor asymmetry in larval zebrafish search pattern behavior. Here, we compare visuomotor asymmetry across several larval teleost species, demonstrating that general motor patterns are variable while behavioral asymmetry is conserved across sighted teleosts, yet not naturally blind cavefish. Our data indicate that visuomotor asymmetry in larval teleosts is a conserved behavior that can be modulated by natural selection against vision. This establishes larval teleosts as a powerful system for dissecting the molecular and evolutionary forces that govern behavioral lateralization, bridging the gap between mechanism and adaptation.