A global analysis of field body temperatures of active squamates in relation to climate and behaviour

SHAHAR DUBINER; ROCÍO AGUILAR ; RODOLFO ANDERSON; DIEGO M. ARENAS MORENO; LUCIANO AVILA; ESTEFANIA BOADA-VITERI; MARTIN CASTILLO; DAVID CHAPPLE; CHRISTIAN O. CHUKWUKA; ALISON CREE; FELIX CRUZ; GUARINO COLLI

Global Ecology and Biogeography

John Wiley and Sons Inc

Año: 2024

Aim: Squamate fitness is affected by body temperature, which in turn is influenced byenvironmental temperatures and, in many species, by exposure to solar radiation. Thebiophysical drivers of body temperature have been widely studied, but we lack an integrativesynthesis of actual body temperatures experienced in the field, and their relationshipsto environmental temperatures, across phylogeny, behaviour and climate.Location: Global (25 countries on six continents).Taxa: Squamates (210 species, representing 25 families).Methods: We measured the body temperatures of 20,231 individuals of squamatesin the field while they were active. We examined how body temperatures vary withsubstrate and air temperatures across taxa, climates and behaviours (basking and dielactivity).Results: Heliothermic lizards had the highest body temperatures. Their body temperatureswere the most weakly correlated with substrate and air temperatures.Body temperatures of non-heliothermicdiurnal lizards were similar to heliothermsin relation to air temperature, but similar to nocturnal species in relation to substratetemperatures. The correlation of body temperature with air and substrate temperatureswas stronger in diurnal snakes and non-heliothermiclizards than in heliotherms.Body-substrateand body-airtemperature correlations varied with mean annual temperaturesin all diurnal squamates, especially in heliotherms. Thermal relations varywith behaviour (heliothermy, nocturnality) in cold climates but converge towards thesame relation in warm climates. Non-heliothermsand nocturnal species body temperaturesare better explained by substrate temperature than by air temperature. Bodytemperature distributions become left-skewedin warmer-bodiedspecies, especiallyin colder climates.Main Conclusions: Squamate body temperatures, their frequency distributions andtheir relation to environmental temperature, are globally influenced by behaviouraland climatic factors. For all temperatures and climates, heliothermic species´ bodytemperatures are consistently higher and more stable than in other species, but in regionswith warmer climate these differences become less pronounced. A comparablevariation was found in non-heliotherms,but in not nocturnal species whose body temperatureswere similar to air and substrate irrespective of the macroclimatic context.