Behaviour 2019
Diet, social complexity, and brain evolution of predatory ants
Frank Azorsa1, Mario L. Muscedere1,2, James F.A. Traniello1,3. 1Department of Biology, Boston University, Boston, MA, United States; 2Undergraduate Program in Neuroscience, Boston University, Boston, MA, United States; 3Graduate Program for Neuroscience, Boston University, Boston, MA, United States

Diet and social complexity are hypothesized to drive brain evolution, but support for these models has been inconsistent. The relative influences of colony size, a proxy for social complexity, and diet can be examined using poneroid ants, a clade known for predatory habits and relatively basal sociality. Many poneroid ant species have evolved as generalist predators of arthropods or specialists limited to centipedes, or termites. Workers forage individually or collectively. We examined how diet and colony size influence brain size and compartmental allometry in poneroid species. We found that brain size scales allometrically with body size, and species with generalist diets and large colonies have large mushroom bodies, which may support behavioral skills required for individual predation. Species with specialist diets and either large or small colonies have larger antennal lobes (dependency on chemical signaling) and an allometrically large central complex (navigation). Results suggest variation in brain size and structure in this clade is primarily due to dietary shifts that influence solitary or cooperative prey capture, colony size, communication, and social interactions.