No evidence for discovery-dominance tradeoffs in Pheidole (Hymenoptera: Formicidae) assemblages

Understanding the mechanisms that allow species coexistence across spatial scales is of great interest to ecologists. Many such proposed mechanisms involve tradeoffs between species in different life-history traits, with distinct tradeoffs being expected to be prevalent at varying temporal and spatial scales. The dominance-discovery tradeoff posits that species differ in their ability to find and use resources quickly, in contraposition to their ability to monopolize those resources, a mechanism analogous to the competition-colonization tradeoff. We investigated the occurrence of this structuring mechanism in Pheidole (Hymenoptera: Formicidae) assemblages in Atlantic Forest remnants. According to the dominance-discovery tradeoff, we should observe a consistent interspecific variation along the axis of discovery and dominance. We established 55 sampling units across two sites, with each unit consisting of a sardine bait monitored for three hours. There was no distinction among Pheidole species in their ability to find or dominate food sources, suggesting that the dominance-discovery tradeoff does not explain their coexistence. The low levels of aggression between Pheidole species could prevent the establishment of dominance hierarchies, whereas the species order of arrival at food sources could allow for resource partitioning through priority effects.