Predators drive selection for adaptive plasticity in prey defense behavior.

This article investigates how fish predation influences adaptive behavioral plasticity in damselfly prey, specifically the Orange Bluet (Enallagma signatum). Using mesocosm experiments and field observations across lakes with varying fish densities, the study demonstrates that fish predation selects for damselflies that exhibit greater plasticity in activity rates—reducing activity when predators are present and increasing it once the threat subsides. The magnitude of this plasticity correlates positively, though modestly, with natural fish densities, suggesting environmental conditions shape the evolution of such plastic responses. These findings support the hypothesis that predator-driven selection can favor reversible behavioral plasticity in prey, potentially mitigating growth costs associated with reduced activity during predation risk.