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

   https://doi.org/10.1111/geb.13808  

   Dubiner, Shahar; Aguilar, Rocío; Anderson, Rodolfo O; Arenas Moreno, Diego M; Avila, Luciano J; Boada‐Viteri, Estefania; Castillo, Martin; Chapple, David G; Chukwuka, Christian O; Cree, Alison; et al (April 2024, Global Ecology and Biogeography)

   Lenoir, Jonathan (Ed.)

   Abstract AimSquamate fitness is affected by body temperature, which in turn is influenced by environmental temperatures and, in many species, by exposure to solar radiation. The biophysical drivers of body temperature have been widely studied, but we lack an integrative synthesis of actual body temperatures experienced in the field, and their relationships to environmental temperatures, across phylogeny, behaviour and climate. LocationGlobal (25 countries on six continents). TaxaSquamates (210 species, representing 25 families). MethodsWe measured the body temperatures of 20,231 individuals of squamates in the field while they were active. We examined how body temperatures vary with substrate and air temperatures across taxa, climates and behaviours (basking and diel activity). ResultsHeliothermic lizards had the highest body temperatures. Their body temperatures were the most weakly correlated with substrate and air temperatures. Body temperatures of non‐heliothermic diurnal lizards were similar to heliotherms in relation to air temperature, but similar to nocturnal species in relation to substrate temperatures. The correlation of body temperature with air and substrate temperatures was stronger in diurnal snakes and non‐heliothermic lizards than in heliotherms. Body‐substrate and body‐air temperature correlations varied with mean annual temperatures in all diurnal squamates, especially in heliotherms. Thermal relations vary with behaviour (heliothermy, nocturnality) in cold climates but converge towards the same relation in warm climates. Non‐heliotherms and nocturnal species body temperatures are better explained by substrate temperature than by air temperature. Body temperature distributions become left‐skewed in warmer‐bodied species, especially in colder climates. Main ConclusionsSquamate body temperatures, their frequency distributions and their relation to environmental temperature, are globally influenced by behavioural and climatic factors. For all temperatures and climates, heliothermic species' body temperatures are consistently higher and more stable than in other species, but in regions with warmer climate these differences become less pronounced. A comparable variation was found in non‐heliotherms, but in not nocturnal species whose body temperatures were similar to air and substrate irrespective of the macroclimatic context. 

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2. Asymmetry of thermal sensitivity and the thermal risk of climate change

   https://doi.org/10.1111/geb.13570  

   Buckley, Lauren B.; Huey, Raymond B.; Kingsolver, Joel G. (July 2022, Global Ecology and Biogeography)

   Abstract AimUnderstanding and predicting the biological consequences of climate change requires considering the thermal sensitivity of organisms relative to environmental temperatures. One common approach involves ‘thermal safety margins’ (TSMs), which are generally estimated as the temperature differential between the highest temperature an organism can tolerate (critical thermal maximum, CT_max) and the mean or maximum environmental temperature it experiences. Yet, organisms face thermal stress and performance loss at body temperatures below their CT_max,and the steepness of that loss increases with the asymmetry of the thermal performance curve (TPC). LocationGlobal. Time period2015–2019. Major taxa studiedAnts, fish, insects, lizards and phytoplankton. MethodsWe examine variability in TPC asymmetry and the implications for thermal stress for 384 populations from 289 species across taxa and for metrics including ant and lizard locomotion, fish growth, and insect and phytoplankton fitness. ResultsWe find that the thermal optimum (T_opt, beyond which performance declines) is more labile than CT_max, inducing interspecific variation in asymmetry. Importantly, the degree of TPC asymmetry increases with T_opt. Thus, even though populations with higher T_opts in a hot environment might experience above‐optimal body temperatures less often than do populations with lower T_opts, they nonetheless experience steeper declines in performance at high body temperatures. Estimates of the annual cumulative decline in performance for temperatures above T_optsuggest that TPC asymmetry alters the onset, rate and severity of performance decrement at high body temperatures. Main conclusionsSpecies with the same TSMs can experience different thermal risk due to differences in TPC asymmetry. Metrics that incorporate additional aspects of TPC shape better capture the thermal risk of climate change than do TSMs. 

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3. Data for: "Lizards in the wind: The impact of wind on the thermoregulation of the common wall lizard"

   https://doi.org/10.17632/6pxkxgs3yz.1  

   Spears, Sierra; Pettit, Ciara; Berkowitz, Sophie; Collier, Simone; Colwell, Cece; Livingston, Ethan H; McQueen, Wyatt; Vaughn, Princeton L; Bodensteiner, Brooke L; Leos-Barajas, Vianey; et al (January 2024, Mendeley Data)

   The following are the data and code that supplied the figures, results, and tables from "Lizards in the wind: The impact of wind on the thermoregulation of the common wall lizard" by Spears et. al., 2024. Published in the Journal of Thermal Biology. 

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4. Keeping it cool to take the heat: tropical lizards have greater thermal tolerance in less disturbed habitats

   https://doi.org/10.1007/s00442-022-05235-3  

   Lopera, Diana; Guo, Kimberly Chen; Putman, Breanna J.; Swierk, Lindsey (August 2022, Oecologia)

   Global climate change has profound effects on species, especially those in habitats already altered by humans. Tropical ectotherms are predicted to be at high risk from global temperature increases, particularly those adapted to cooler temperatures at higher altitudes. We investigated how one such species, the water anole (Anolis aquaticus), is affected by temperature stress similar to that of a warming climate across a gradient of human-altered habitats at high elevation sites. We conducted a field survey on thermal traits and measured lizard critical thermal maxima across the sites. From the field survey, we found that (1) lizards from the least disturbed site and (2) operative temperature models of lizards placed in the least disturbed site had lower temperatures than those from sites with histories of human disturbance. Individuals from the least disturbed site also demonstrated greater tolerance to high temperatures than those from the more disturbed sites, in both their critical thermal maxima and the time spent at high temperatures prior to reaching critical thermal maxima. Our results demonstrate within-species variability in responses to high temperatures, depending on habitat type, and provide insight into how tropical reptiles may fare in a warming world. 

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5. Comparison of Hydric and Thermal Physiology in an Environmentally Diverse Clade of Caribbean Anoles

   https://doi.org/10.1093/icb/icae030  

   Alomar, Nathalie; Bodensteiner, Brooke_L; Hernández-Rodríguez, Isabela; Landestoy, Miguel_A; Domínguez-Guerrero, Saúl_F; Muñoz, Martha_M (May 2024, Integrative And Comparative Biology)

   Synopsis As the world becomes warmer and precipitation patterns less predictable, organisms will experience greater heat and water stress. It is crucial to understand the factors that predict variation in thermal and hydric physiology among species. This study focuses on investigating the relationships between thermal and hydric diversity and their environmental predictors in a clade of Hispaniolan anole lizards, which are part of a broader Caribbean adaptive radiation. This clade, the “cybotoid” anoles, occupies a wide range of thermal habitats (from sea level to several kilometers above it) and hydric habitats (such as xeric scrub, broadleaf forest, and pine forest), setting up the possibility for ecophysiological specialization among species. Among the thermal traits, only cold tolerance is correlated with environmental temperature, and none of our climate variables are correlated with hydric physiology. Nevertheless, we found a negative relationship between heat tolerance (critical thermal maximum) and evaporative water loss at higher temperatures, such that more heat-tolerant lizards are also more desiccation-tolerant at higher temperatures. This finding hints at shared thermal and hydric specialization at higher temperatures, underscoring the importance of considering the interactive effects of temperature and water balance in ecophysiological studies. While ecophysiological differentiation is a core feature of the anole adaptive radiation, our results suggest that close relatives in this lineage do not diverge in hydric physiology and only diverge partially in thermal physiology. 

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