Running performance with emphasis on low temperatures in a Patagonian lizard, Liolaemus lineomaculatus

Abstract

Lizard activity and endurance of cold climate is regulated by several factors such as evolutionary potential, acclimatization capacity, physiological tolerance, and locomotion among thermally advantageous microenvironments. Liolaemus lineomaculatus, a lizard inhabiting a wide range of cold environments in Patagonia, provides an excellent model to test interpopulation variability in thermal performance curves (TPCs) and usage of microhabitats. We obtained critical thermal minima and maxima, and performed running trials at eight temperatures using lizards from both a temperate-site (high-altitude) population at 42° S and a cold-site population at 50° S. The availability of environmental temperatures for running performance in open ground and in potential lizard refuges were recorded, and showed that lizards in the temperate site had a greater availability of thermal environments offering temperatures conducive to locomotion. Generalized additive mixed models showed that the two populations displayed TPCs of different shapes in 0.15 m runs at temperatures near their optimal temperature, indicating a difference in thermal sensitivity at high temperatures. However, the rest of the locomotor parameters remained similar between Liolaemus lineomaculatus from thermal and ecological extremes of their geographic distribution and this may partly explain their ability to endure a cold climate.

Latitudinal pattern of the thermal sensitivity of running speed in the endemic lizard Liolaemus multimaculatus

“…Liolaemid lizards living in the temperate cold climate of Patagonia show a remarkable capacity to endure low temperatures, since their locomotor performance capacities and thermal sensitivities are adjusted at temperatures that are suboptimal for lizards from lower latitude (Cecchetto et al . 2020). The thermal optimum and the thermal performance breadth of L. multimaculatus showed weak to null associations with thermal tolerance breadth.…”

“…2017; Cecchetto et al . 2020). Discerning the physiological responses in the context of climatic variability due to latitude is an important task that contributes to an understanding of theoretical topics in biology, and it can be useful in establishing management strategies in view of future scenarios of environmental change.…”

“…We expected the individuals of L. multimaculatus from higher latitudes to have broader thermal tolerance breadth and thermal performance breadth than the individuals from lower latitudes. Second, we expected a locally adapted response in liolaemid lizards (Labra et al 2009;Cecchetto et al 2020); therefore, individuals of L. multimaculatus from higher latitudes were expected to show relatively lower thermal optimum and decreased limits of thermal performance breadth in comparison with those from lower latitudes. Third, Lizards from low-temperature environments would have higher physiological performance at low temperatures than those from warm-temperature environments (Hare et al 2010); therefore, at relatively low temperatures, the V max of L. multimaculatus individuals from higher latitudes would be higher than that of individuals inhabiting lower latitudes.…”

Integrating trait-based movement into mechanistic predictions of thermal performance

“…Overall, this suggests that incorporating the temperature-dependence of movement is important for predicting net energy gain across the range of temperatures observed in nature. However, generalizations across taxonomic groups are also possible using allometric but temperature-independent scaling relationships for movement speed, for which more data is available (Angilletta et al 2007;Hirt et al 2017;Rezende & Bozinovic 2019;Cecchetto et al 2020). Furthermore, it stresses the dominant importance of the temperature-dependence of prey density and parallels findings of models and experiments showing that food intake strongly affects optimum temperatures and upper thermal limits (Brett 1970;Thomas et al 2017 Lister & Garcia 2018) will thus enhance the vulnerability of ectotherms to warming (Huey & Kingsolver 2019).…”

Vulnerability to climate change of a microendemic lizard species from the central Andes

“…To determine the available spatiotemporal heterogeneity of the microenvironmental temperatures for thermoregulation, operative temperatures (T e , sensu Bakken 93 ) were obtained using nine polyvinyl chloride (PVC) pipe models connected to external dataloggers (HOBO, U23-003, T°/T°C ± 1 °C) during the collection of lizards. The model with the greatest correspondence of thermal data to reflect the lizard T b was a PVC pipe (80 mm length × 2.15 mm thickness) sealed at both ends with silicone Fastix (Regression: Adjusted R 2 = 0.846, N = 2836, slope = 1.09, confidence interval = 1.05 ‒ 1.14) 94 , 95 . Subsequently, the models were deployed in the study area in the most representative microhabitats used by L. montanezi : (i) Bare soil with sunny, sandy substrate, (ii) Bare soil with shady, sandy substrate (beneath shrubs), and (iii) Weathered rocks in the shade beneath shrubs (3 microhabitats × 3 replicates).…”