Variation in field body temperature and total evaporative water loss along an environmental gradient in a diurnal ectotherm

Abstract

The maintenance of optimal body temperatures has profound consequences on all aspects of ectotherms life history, like fitness and performance, and has been the subject of research for decades. In contrast, for reptiles, comparatively less is known on the potential effects of water balance on physiology, ecology and behaviour. In recent years, several recent studies are pointing out the importance of studying thermoregulation and water balance within the same framework. Here, we used a Mediterranean lizard, Psammodromus algirus, to investigate how field body temperature and water loss rates may vary among populations, between sexes and along an altitudinal gradient. We found little variation in field body temperatures among populations, while within each population, field body temperature may change daily, seasonally and differ between sexes. On the contrary, water loss rates decreased with elevation and showed no seasonal trend or difference between sexes. Microclimatic data indicated that highland lizards experienced more fluctuating conditions, a factor that may explain their lower water loss rates. Other factors, like inter‐population differences in ectoparasite intensity, might also contribute in explaining the observed patterns. We present here the first data for a lacertid lizard on the inter‐population variability and sexual difference in water loss rates and point out that water balance may play a fundamental role in regulating lizard activity during the hottest and driest period of the year.

Cellular and whole‐organism effects of prolonged versus acute heat stress in a montane, desert lizard

“…This result was consistent across the transplant treatment in Experiment 2, whether lizards were transplanted upwards in elevation to a cooler climate, or downward in elevation to a warmer climate. In another montane lizard, Psammodromus algirus , rates of water loss were higher at lower elevations and decreased with elevation, which the authors attribute to greater fluctuations in microclimate experienced by high‐elevation lizards (Sannolo et al, 2020). In our study, transplanted lizards exhibited a decrease in water content regardless of either their site of origin or the site to which they were transplanted.…”

Thermal adaptation revisited: How conserved are thermal traits of reptiles and amphibians?

“…Overall, existing evidence suggests that thermoregulatory behavior is a plastic trait that can be immediately adjusted based on prevailing environmental conditions (e.g., Caldwell et al, 2017; Domínguez–Guerrero et al, 2019; Ortega et al, 2016a; Refsnider et al, 2018). Nonetheless, behavioral plasticity can be confounded by a number of variables, such as season, life stage, hydric environment, reproductive condition, or health status (A. E. Conover et al, 2015; Gatten, 1974; Isaac & Gregory, 2004; Rozen‐Rechels et al, 2019; Ryan et al, 2016; Sannolo et al, 2019; van Damme et al, 1987).…”

Short-term changes in air humidity and water availability weakly constrain thermoregulation in a dry-skinned ectotherm

“…lizard is a species less resistant to water loss than Podarcis lizards [25,38,59]. It is difficult to fully explain these differences since experimental protocols of the two studies are not identical, but one possibility is that common lizards also adjusted their locomotor activity in the thermal gradient by moving less often in drier conditions.…”