Do palatable prey benefit from aposematic neighbors?

Synergistic selection can promote the evolution of aposematism. This requir es, however, that palatable prey without signals do not benefit from their aposematic neighbours. In order to test this requirement, we designed an ex periment using artificially aposematic mealworm larvae and palatable contro l larvae. As a predator we used great tits. Birds encountered five types of groups: pure groups of aposematic or palatable prey items and mixed groups of palatable and aposematic items or single palatable and single aposemati c preys. Survival of aposematic items both in pure groups and for solitary items was high. Unexpectedly, birds also avoided mixed groups. Survival of palatable prey with aposematic neighbors was significantly higher compared to solitary palatables and to those with palatable neighbors. Thus, our res ults suggest that the protection through association gained by palatable in dividuals should be taken into account when evaluating evolutionary consequ ences of synergism for the evolution of aposematism.