Complex behavioral manipulation drives mismatch between host and parasite diversity

Abstract

Parasites and hosts are intimately associated such that changes in the diversity of one partner are thought to lead to changes in the other. We investigated this linked diversity hypothesis in a specialized ant-Ophiocordyceps system in three forests across 750 km in Central Amazonia. All species belonging to the fungal genus Ophiocordyceps associated with ants have evolved some degree of behavioral control to increase their own transmission, but the leaf-biting behavior is the most complex form of host manipulation. Such a system requires control of the mandibular muscles and a distinct shift in behavior, from climbing vegetation to walking on leaves to rasping leaf veins in the seconds before death. The need to induce complex behavior may limit host availability and represent a constraint on parasite diversity. The consequence for community structure is that complex behavioral manipulation leads to a mismatch between ant hosts and the diversity of their fungal parasites.