Ant thermal tolerance: a review of methods, hypotheses, and sources of variation

Authors: Roeder, Karl; ROEDER, DIANE - University Of Illinois; BUJAN, JELENA - University Of Lausanne

Submitted to: Annals of the Entomological Society of America
Publication Type: Review Article
Publication Acceptance Date: 4/12/2021
Publication Date: 5/11/2021
Citation: Roeder, K.A., Roeder, D.V., Bujan, J. 2021. Ant thermal tolerance: a review of methods, hypotheses, and sources of variation. Annals of the Entomological Society of America. https://doi.org/10.1093/aesa/saab018.
DOI: https://doi.org/10.1093/aesa/saab018

Interpretive Summary: Most animals, including insects, are ectotherms whose physiology is constrained by temperature. Consequently, interest in traits like thermal tolerance that enable insects to survive and thrive in variable climates has steadily increased over the past few decades. The aim of our review is to synthesize the published literature on the thermal tolerance of one ecologically important group of insects—the ants. We begin our review with discussion on common methods and offer several methodological caveats for consideration. We next describe patterns and hypotheses for ant thermal tolerance along environmental gradients that vary with latitude, elevation, urbanization, seasons, and days. Furthermore, we discuss other sources of variation and highlight several topics we think should be of interest to thermal biologists.

Technical Abstract: 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 steadily increased over the past few decades. Here we synthesize the published literature on the thermal tolerance of ants. We begin our review with discussion on 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 common patterns and hypotheses for ant thermal tolerance along spatial and temporal temperature gradients. Spatially, we focus on thermal tolerance 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.