Torpor energetics are related to the interaction between body mass and climate in bats of the family Vespertilionidae

Abstract

AbstractTorpor is an adaptive strategy that allows animals to cope with energy limitations under adverse environmental conditions. In birds and mammals, intrinsic and extrinsic factors such as body mass (Mb) and ambient temperature (Ta) are well established triggers of torpor. Interestingly, the interplay betweenMband climate with differentTaon torpor traits in bats remains unexplored. Using open flow respirometry, we calculatedTaupon entering torpor (Tat), the reduction in torpid metabolic rate relative to the basal metabolic rate (TMRred), theTaat which torpor metabolic rate reached its minimum (Taadjust), and minimum torpid metabolic rate (TMRmin) in 11 bat species of the family Vespertilionidae that differ inMbfrom warm and cold climates. We also includedTMRmindata retrieved through a bibliography review. We tested the effects ofMband climate on torpor traits using mixed-effect phylogenetic models. All models showed a significant interaction betweenMband climate. This interaction was inversely related toTat,TMRred,Taadjust, and positively related toTMRmin. These results are likely explained by the differences inMband the metabolic rate of bats from different climates, which may allow individuals to express torpor in places with differentTa. Further studies to assess torpor use in bats of different climates are proposed.Summary statementThe interaction between body mass and climate influences torpor energetics in bats of the family Vespertilionidae. As a result, torpid traits change based on body mass and climate.