Tradeoffs, competition and coexistence in eastern deciduous forest ant communities

KATHARINE L. STUBLE; MARIANO A. RODRIGUEZ CABAL; GAIL L. MCCORMICK; NATHAN J. SANDERS

Copenhague

Congreso; XVI Congress in Copenhagen - Denmark - International Union for the Study of Social Insects; 2010

What factors promote coexistence in local communities? Two ideas have received much attention: tradeoffs and resource partitioning. Tradeoffs with the potential to promote coexistence among ant species include the dominance-discovery tradeoff and the dominance-thermal tolerance tradeoff, both of which suggest that behaviorally dominant ants tend to be poor at other aspects of food acquisition, including discovering food resources and foraging under a wide range of conditions. Niche partitioning, including partitioning of space and foraging conditions, is another potential mechanism which might promote coexistence. We examined the evidence for 1) the dominance-discovery tradeoff, 2) the dominance-thermal tolerance tradeoff, 3) spatial niche segregation, 4) temporal niche partitioning, and 5) temperature-based niche partitioning in structuring an ant community at a forest site in the eastern US. Many of these mechanisms have been tested in a single system, but never, to our knowledge, have all of these mechanisms been examined simultaneously in a single system. We found no evidence for tradeoffs or spatial niche partitioning. However, we observed significant segregation of foraging times on a daily time scale, with behaviorally dominant ants most frequently observed on baits in the middle of the night while subdominant ants were observed most frequently on baits during the day. Together, these results suggest that the coexistence of ants in the study system may be promoted by the ability of species to forage at different times, thus minimizing direct encounters.