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Cold comfort: metabolic rate and tolerance to low temperatures predict latitudinal distribution in ants

Willot, Quentin1; Ørsted, Michael2; Malte, Hans1; Overgaard, Johannes1

Published Sep 07, 2023 on Dryad. https://doi.org/10.5061/dryad.573n5tbc5

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Sep 07, 2023 version files 367.26 KB

Abstract

Metabolic compensation has been proposed as a mean for ectotherms to cope with colder climates. For example, under the metabolic cold adaptation and the metabolic homeostasis hypotheses (MCA and MHH), it has been formulated that cold-adapted ectotherms should display both higher (MCA) and more thermally sensitive (MHH) metabolic rates (MRs) at lower temperatures. However, whether such compensation can truly be associated with distribution, and whether it interplays with cold-tolerance to support species’ climatic niches, remains largely unclear despite broad ecological implications thereof. Here, we teased apart the relationship between MRs, cold-tolerance, and distribution, to test the MCA/MHH among 13 ant species. We report clear metabolic compensation effects, consistent with the MCA and MHH, where MR parameters strongly correlated with latitude and climatic factors across species’ distributions. The combination of both cold-tolerance and MR further upheld the best predictions of species’ climatic niches. To our knowledge, this is the first study showing that the association of metabolic data with cold-tolerance supports better predictive models of climatic temperature and distribution in social insects than models including cold-tolerance alone. These results also highlight that adaptation to higher latitudes in ants involved adjustments of both cold-tolerance and MRs, to allow this extremely successful group of insects to thrive under colder climates.