Discovery-defense strategy as a mechanism of social foraging of ants in tropical rainforest canopies

Many hypotheses have been proposed to explain the coexistence of ants sharing similar food resources, including ecological trade-offs, however, these hypotheses have mostly been tested in ground-dwelling ant communities. For instance, the discovery-dominance trade-off hypothesis states that species with overlapping food resources differ in their ability to find and dominate resources. However, ant species may use different strategies to share food resources, including discovery-defense, in which the first species to arrive at a food resource maintains control of it. Here, we evaluated whether the discovery-dominance trade-off hypothesis, or the discovery-defense strategy could be a mechanism that promotes coexistence of ant species in the canopy of highly diverse tropical forest canopies. We evaluated the succession of ant species on 72 baits exposed on 24 trees during 13 observation periods (15–195 min) in the canopy of a tropical rain forest in Mexico. In general, we observed little variation in ant species composition (i.e., low β-diversity values) during the 195 min of bait exposure. Moreover, we found that ant species with the greatest ability to discover new food resources were those that dominated them. These findings empirically show that the discovery-defense strategy can be a social foraging strategy in rain forest canopy ants and reject the discovery-dominance trade-off. In short, our results highlight the importance of the discovery of a food resource in the canopy of a tropical rain forest, allowing it to be dominated.