Thermoregulatory behaviour explains countergradient variation in the upper thermal limit of a rainforest skink

Llewelyn, John, Macdonald, Stewart, Hatcher, Amberlee, Moritz, Craig, and Phillips, Ben L. (2017) Thermoregulatory behaviour explains countergradient variation in the upper thermal limit of a rainforest skink. Oikos, 126 (5). pp. 748-757.

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The vulnerability of a terrestrial ectotherm to high environmental temperatures depends on the animal's thermal physiology and thermoregulatory behaviour. These variables - environment, physiology, and behaviour - interact with each other, complicating assessment of species vulnerability to global warming. We previously uncovered a counterintuitive pattern in rainforest sunskinks Lampropholis coggeri: a negative relationship between their critical thermal maximum (CTmax) and the temperature of their environment. Could this result be explained by a three-way interaction between environment, physiology, and behaviour? Here we find that sunskink thermal preference is correlated positively with CTmax, but, importantly, skinks from hotter environments prefer lower temperatures than conspecifics from cooler environments. In an acclimation experiment, we find that CTmax is plastic and shifts in alignment with acclimation temperature. We also found heritable variation in this trait in a common garden study, but this variation was small relative to the plastic shifts observed in CTmax. Thus, our previous observation of a negative correlation between field CTmax and temperature is explained, at least in part, by the lizard's thermoregulatory behaviour: lizards from hot environments preferentially choose cool microenvironments, and their physiology acclimates to these cooler experienced temperatures. Our results suggest that behavioural adjustments to the environment can produce countergradient variation in physiological traits. More broadly, our work underscores the importance of interactions between environment, behaviour, and physiology in ectotherms. Understanding these interactions will be crucial in assessing vulnerability to climate change.

Item ID: 50448
Item Type: Article (Research - C1)
ISSN: 1600-0706
Funders: Australian Research Council (ARC), CSIRO/JCU Tropical Landscapes Joint Venture
Projects and Grants: ARC DP1094646, ARC 130100318
Date Deposited: 20 Sep 2017 09:10
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310403 Biological adaptation @ 50%
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310912 Comparative physiology @ 50%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960301 Climate Change Adaptation Measures @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 50%
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