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Hot and bothered: alterations in faecal glucocorticoid metabolite concentrations of the sungazer lizard, Smaug giganteus, in response to an increase in environmental temperature

Hot and bothered: alterations in faecal glucocorticoid metabolite concentrations of the sungazer... Despite the commonly held belief that reptiles are immune to extreme temperatures, global warming is predicted to result in the loss of 40% of all reptile species by 2080. In order to understand the effects of elevated temperature on African reptile physiology and health, additional research is required. We studied the physiological stress response of sungazer lizards (Smaug giganteus) facing elevated temperatures within captivity. Control animals (1M, 2F) were kept at 30 °C throughout the 13-week study period. Test animals (1M, 2F) were exposed to 30 °C for four weeks (stage 1), 39 °C for six weeks (stage 2) and 30 °C for three weeks (stage 3). Faecal samples were collected from both control and test animals to monitor faecal glucocorticoid metabolite (fGCM) concentrations as a proxy of physiological stress. Although the fGCM levels of control females remained constant, test females showed an acute fGCM increase following the increase and subsequent decrease of temperatures. The test male had significantly higher fGCM levels during stage 3, compared with stage 1 and 2. The control male, although displaying constant fGCM levels throughout the study, had higher fGCM levels than the test male. The results indicate that a considerable temporal increase in environmental temperature did not lead to chronically elevated adrenocortical activity in sungazer lizards. It is likely that inherent traits within the species allow the species to adapt to such changes. Furthermore, the endangered status of the species and limited availability of study animals restricted the sample size in this study to a few, captive-based lizards. Therefore, although our results are an important addition to reptile conservation, they should be extrapolated to free-ranging populations with caution. Future research should consider the effects of chronically elevated temperature in relation to water and food shortages, as well as interindividual variation in physiological responses. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Zoology Taylor & Francis

Hot and bothered: alterations in faecal glucocorticoid metabolite concentrations of the sungazer lizard, Smaug giganteus, in response to an increase in environmental temperature

Scheun, J; Campbell, R; Ganswindt, A; McIntyre, T
African Zoology , Volume 56 (3): 9 – Jul 3, 2021
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Hot and bothered: alterations in faecal glucocorticoid metabolite concentrations of the sungazer lizard, Smaug giganteus, in response to an increase in environmental temperature

Abstract

Despite the commonly held belief that reptiles are immune to extreme temperatures, global warming is predicted to result in the loss of 40% of all reptile species by 2080. In order to understand the effects of elevated temperature on African reptile physiology and health, additional research is required. We studied the physiological stress response of sungazer lizards (Smaug giganteus) facing elevated temperatures within captivity. Control animals (1M, 2F) were kept at 30 °C throughout...
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Publisher
Taylor & Francis
Copyright
© 2021 Zoological Society of Southern Africa
ISSN
2224-073X
eISSN
1562-7020
DOI
10.1080/15627020.2021.1980103
Publisher site
See Article on Publisher Site

Abstract

Despite the commonly held belief that reptiles are immune to extreme temperatures, global warming is predicted to result in the loss of 40% of all reptile species by 2080. In order to understand the effects of elevated temperature on African reptile physiology and health, additional research is required. We studied the physiological stress response of sungazer lizards (Smaug giganteus) facing elevated temperatures within captivity. Control animals (1M, 2F) were kept at 30 °C throughout the 13-week study period. Test animals (1M, 2F) were exposed to 30 °C for four weeks (stage 1), 39 °C for six weeks (stage 2) and 30 °C for three weeks (stage 3). Faecal samples were collected from both control and test animals to monitor faecal glucocorticoid metabolite (fGCM) concentrations as a proxy of physiological stress. Although the fGCM levels of control females remained constant, test females showed an acute fGCM increase following the increase and subsequent decrease of temperatures. The test male had significantly higher fGCM levels during stage 3, compared with stage 1 and 2. The control male, although displaying constant fGCM levels throughout the study, had higher fGCM levels than the test male. The results indicate that a considerable temporal increase in environmental temperature did not lead to chronically elevated adrenocortical activity in sungazer lizards. It is likely that inherent traits within the species allow the species to adapt to such changes. Furthermore, the endangered status of the species and limited availability of study animals restricted the sample size in this study to a few, captive-based lizards. Therefore, although our results are an important addition to reptile conservation, they should be extrapolated to free-ranging populations with caution. Future research should consider the effects of chronically elevated temperature in relation to water and food shortages, as well as interindividual variation in physiological responses.

Journal

African Zoology – Taylor & Francis

Published: Jul 3, 2021

Keywords: adrenocortical; climate change; glucocorticoids; reptile physiology

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