No evidence for dominance–discovery trade-offs 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 trade-offs between species in different life-history traits, with distinct trade-offs being expected to be prevalent at varying temporal and spatial scales. The dominance–discovery trade-off posits that species differ in their ability to find and use resources quickly, in contrast to their ability to monopolize those resources, a mechanism analogous to the competition-colonization trade-off. We investigated the occurrence of this structuring mechanism in the genus Pheidole Westwood, 1839 (Hymenoptera: Formicidae) assemblages in Atlantic Forest remnants. According to the dominance–discovery trade-off, consistent interspecific variation should be observed 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 3 h. There was no distinction among Pheidole species in their ability to find or dominate food sources, suggesting that the dominance–discovery trade-off 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.