Ants (Hymenoptera: Formicidae) are a conspicuous group of ectotherms whose behavior, distribution, physiology, and fitness are regulated by temperature. Consequently, interest in traits like thermal tolerance that enable ants to survive and thrive in variable climates has increased exponentially over the past few decades. Here, we synthesize the published literature on the thermal tolerance of ants. We begin our review with discussion of common metrics: critical thermal limits, lethal thermal limits, knock-down resistance, chill-coma recovery, and supercooling. In particular, we highlight the ways each thermal metric is quantified and offer a set of methodological caveats for consideration. We next describe patterns and hypotheses for ant thermal tolerance along spatial and temporal temperature gradients. Spatially, we focus on relationships with latitude, elevation, urbanization, and microclimate. Temporally, we focus on seasonal plasticity, daily variation, dominance-thermal tolerance tradeoffs, and acclimation. We further discuss other sources of variation including evolutionary history, body size, age, castes, and nutrition. Finally, we highlight several topics of interest to ant thermal biologists, ranging in scope from methods development to the impacts of climate change.

1. To achieve numerical dominance, an ectotherm consumer requires a sizeable abiotic window in which it can forage. Here we explore how one abiotic factor, temperature, provides opportunity and regulates the impact of the invasive red imported fire ant, Solenopsis invicta, on an urban ant assemblage.2. We first quantified S. invicta's ability to outcompete native species by contrasting its foraging biomass to that of its potential competitors. In doing so, we found that S. invicta deployed more ant biomass at baits than the estimated whole colony biomass of three of the four co-occurring native species. It did so across c. 75% of the hours in a summer day, those hours below its thermal maximum of 49 ∘ C. Higher thermal maxima allowed two native species to avoid encountering workers of S. invicta.3. Exclosure experiments revealed that a third species, Dorymyrmex flavus, more similar in body size and thermal tolerance to S. invicta, was competitively suppressed by the invasive. Carbon and nitrogen stable isotope analysis suggests that D. flavus' persistence is likely due to dietary differences. 4. Although thermal and dietary traits help predict how species coexist in this invaded assemblage, one key to S. invicta's success is likely to be its ability to forage in all but 6 h of a summer's day.

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

No abstract