The evolution of foraging behavior in ants (Hymenoptera: Formicidae)

Cooperative foraging behavior is a key characteristic of ants. A variety of foraging behaviors are present across this animal family, but little is known of how these behavioral traits evolved and differentiated. In addition, classification of these foraging behaviors has been inconsistent across the literature. Using four classification methods, we infer the ancestral foraging states across the Formicidae, as well as test the transitions between and resulting speciation due to foraging behavior. Our study reinforces the hypothesis that solitary foraging behaviors are ancestral to cooperative foraging behaviors, with strong support for solitary foraging at the root of the phylogeny. We find that cooperative foraging behaviors rarely revert to solitary, and that cooperative behaviors do not often transition between one another. While our findings are consistent across all four classification methods, they are limited by a small behavioral dataset relative to the number of living ant species-we therefore assert that behavioral data are as important as genetic data, and that further effort for detailed, published observations be maintained.