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

Abstract

Thermoregulation is critical for ectotherms as it allows them to maintain their body temperature close to an optimum for ecological performance. Thermoregulation includes a range of behaviors that aim at regulating body temperature within a range centered around the thermal preference. Thermal preference is typically measured in a thermal gradient in fully-hydrated and post-absorptive animals. Short-term effects of the hydric environment on thermal preferences in such set-ups have been rarely quantified in dry-skinned ectotherms, despite accumulating evidence that dehydration might trade-off with behavioral thermoregulation. Using experiments performed under controlled conditions in climatic chambers, we demonstrate that thermal preferences of a ground-dwelling, actively foraging lizard (Zootoca vivipara) are weakly decreased by a daily restriction in free-standing water availability (less than 0.5°C contrast). The influence of air humidity during the day on thermal preferences depends on time of the day and sex of the lizard, and is generally weaker than those of of free-standing water (less than 1°C contrast). This shows that short-term dehydration can influence, albeit weakly, thermal preferences under some circumstances in this species. Environmental humidity conditions are important methodological factors to consider in the analysis of thermal preferences.

Wind of change: a diurnal skink thermoregulates between cooler set-points and for an increased amount of time in the presence of wind

“…Increased time thermoregulating to compensate for lower T b has been recorded in the lizard Zootoca vivipara ; individuals living higher on an altitudinal gradient, where available operative temperatures were lower, compensated by spending 50% more time thermoregulating ( Gvoždík, 2002 ). The maintenance of similar mean temperatures across treatments by McCann's skink, however, differs from studies that have recorded lizards selecting cooler temperatures when dehydrated ( Le Galliard et al, 2021 ; Sannolo and Carretero, 2019 ). This difference may be due to skinks in this experiment thermoregulating in a way that anticipated a risk of dehydration while not necessarily becoming significantly dehydrated over the duration of the test.…”

“…Perhaps of most relevance to our results, hydration state has been shown to affect thermal preferences in lizards. The lizard Zootoca vivipara thermoregulated between cooler set-points and had a lower mean T b when water was withheld for a day ( Le Galliard et al, 2021 ). Dehydration lowered the mean T b and preferred body temperatures for four species of wall lizard ( Podarcis ), resulting in left-skewed body temperature distributions ( Sannolo and Carretero, 2019 ).…”

“…This function calculates revised marginal and conditional R 2 values after Nakagawa et al (2017) . To compare significantly different treatments, we used the ‘glht’ function in the package multcomp ( ; Hothorn et al, 2008 ) to perform a Tukey multiple-comparison test and calculate pairwise P- values adjusted using the Holm method ( Holm, 1979 ).…”

Climate aridity and habitat drive geographical variation in morphology and thermo-hydroregulation strategies of a widespread lizard species

“…Another possibility is that the relatively smaller Tpref of wall lizards reflects adjustments to water limitation and habitat aridity in their native population, as shown in laboratory experiments (Sannolo & Carretero, 2019;Le Galliard et al, 2021b).…”

Duration of Low Temperature Exposure Affects Egg Hatching of the Colorado Potato Beetle and Emergence of Overwintering Adults

“…Temperature is one of the most important environmental factors affecting many aspects of the life cycles of insects [14]. Thermoregulation is critical for ectotherms as it allows them to maintain their body temperature close to an optimum for ecological performance, endotherms able to regulate their own body temperature, whereas ectotherms depend on the ambient temperature, so they depend on their behavior, physiology, morphology, etc., to regulate the body's heat emissions or absorb heat from the outside environment to improve their body temperatures [15][16][17][18][19][20]. The fluctuations are larger than extreme high and low temperatures and can affect insect activities [21,22].…”