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.
Highlights
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
Low environmental temperatures can be detrimental to vital activities and compromise s urvival[4,24,25,26], unless the population modifies its thermal performance curves (TPCs), its thermal tolerance breadth (TTB), or makes behavioural adjustments via thermoregulation, modification of the daily hours of activity, or by choosing appropriate refuges to spend inactive time[27,28]
Liolaemids living in the temperatecold climate of Patagonia showed a remarkable capacity to endure low temperatures, being active at suboptimal temperatures and modifying thermoregulatory behaviour according to the availability of microenvironments for thermoregulation (e.g. Liolaemus pictus argentinus[36], L. bibronii, L. boulengeri[37], L. sarmientoi, L. magellanicus38)
Summary
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. In temperate and cold environments lizards would still greatly benefit from mechanisms that allow them to be active at low temperatures, even at suboptimal levels of performance, to take advantage of the scant and irregularly available thermal resources in harsh, cold environments. In this regard, lizards can widen their thermal tolerance breadths, modify thermoregulatory behaviour and activity patterns, and be as active at lower body temperatures as are populations in warmer environments[10,29,30,31,32,33]. Liolaemids living in the temperatecold climate of Patagonia showed a remarkable capacity to endure low temperatures, being active at suboptimal temperatures and modifying thermoregulatory behaviour according to the availability of microenvironments for thermoregulation (e.g. Liolaemus pictus argentinus[36], L. bibronii, L. boulengeri[37], L. sarmientoi, L. magellanicus[38])
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