Print PageArthropods such as ants comprise a dominant fraction of forest ecosystems and provide and influence several ecosystem services. Their sensitivity to temperature suggests that ants will respond to rapid climate change. However, while important, little empirical work has examined how the abundance, composition and behavior of ants and other arthropods may change under climate warming. Furthermore, experiments that examine responses of any taxa across large geographic areas are lacking. In order to understand how ants may respond to climate warming across large geographic areas, we performed controlled, common garden experiments with and thermal tolerance assays for ants of eastern US forests. We collected ant colonies along a latitudinal gradient between Massachusetts and North Carolina and placed them in common conditions that resemble average temperatures near the northern (Harvard Forest, MA) reach of the species’ geographic ranges, near the southern (Duke Forest, NC) reaches of the species’ ranges, and locales farther south (Florida). We tracked brood production and mortality for three months and quantified the thermal tolerances of colonies used in the common garden experiment to determine if ant abundance and assemblage composition will be affected differently across large geographic areas.
Results/Conclusions
Our findings suggest that ant responses to warming will vary by species and latitude. Overall, survival and brood production were reduced in the warmest temperature treatments, particularly for colonies collected in northern locales. At the warmest temperatures, Aphaenogaster rudis colonies had high mortality within two weeks, potentially due to over over-exertion from increased foraging. However, the other species studied had relatively high survival at this stage of the experiment. The thermal tolerance of southern ants had a greater mean and variance than the ants collected from more northern locales. These results suggest that ants at northern locales may not benefit from warming and therefore may decline rather than shift northward under climate change, and the composition of local ant assemblages may be altered since responses differ by species. This may lead to disproportionate changes in some ecosystem services, such as seed dispersal, provided by ants.
