Changes in thermal quality of the environment along an elevational gradient affect investment in thermoregulation by Yarrow’s spiny lizards

Abstract

Body temperature affects physiological processes and, consequently, is assumed to have a large impact on fitness. Lizards need to thermoregulate behaviourally to maintain their body temperature within a range that maximizes performance, but there are costs associated with thermoregulation. The thermal quality of an environment directly affects the amount of time and energy that must be invested by an individual to maintain an optimal body temperature for performance; time and energy are major costs of thermoregulation. According to Huey and Slatkin's (Q. Rev. Biol. 1976, 363) cost-benefit model of thermoregulation, lizards should only thermoregulate when the benefits outweigh the costs. Thus, in habitats of poor thermal quality, lizards should invest less into thermoregulation. We tested the hypothesis that the thermal quality of an environment dictates investment in thermoregulation across an elevational gradient. Increases in elevation are accompanied by decreases in temperature and therefore thermal quality. We recorded body temperatures of Yarrow's spiny lizards (Sceloporus jarrovii) at ten talus slopes along an elevational gradient of over 1000 m. We found a significant positive relationship between elevation and effectiveness of thermoregulation, opposite to the prediction of the cost-benefit model of thermoregulation. This suggests that the disadvantages of thermoconformity may be greater than the costs of thermoregulating as habitats become more thermally challenging.

Intra-population variation of body temperature of the lizard Sceloporus anahuacus (Squamata: Phrynosomatidae) in Sierra del Ajusco, Mexico

“…Such as S. anahuacus, there are other Sceloporus species that show a low Tb like S. malachiticus (Tb = 28.6 °C; Vial, 1984), S. mucronatus mucronatus (Tb = 29.4 ± 0.7 °C; Lemos-Espinal et al, 1997a), S. bicanthalis (Tb = 28.8 ± 0.69 °C; Andrews et al, 1999) and S. palaciosi (Tb = 27.82 ± 5.31 °C;Güizado-Rodríguez et al, 2011). This low Tb is presumably due to thermal constraints imposed by the spatial and temporal distribution of environmental temperatures that determine daily and seasonal activity because usually at high elevations, thermal quality is low (Lymburner & Blouin-Demers, 2020). Lara-Reséndiz et al, (2014) evaluated the thermal habitat quality of a lizard community along an altitude gradient, in order to determine if thermal environment has an effect on distribution and thermal ecology.…”

Thermal biology of two sympatric Lacertids lizards (Lacerta diplochondrodesandParvilacerta parva) from Western Anatolia

“…Body temperatures of ectotherms, including reptiles, strongly depend on thermal properties of their microhabitats (Goller et al, 2014; Gómez Alés et al, 2017; Huey and Slatkin, 1976; Ortega and Pérez-Mellado, 2016). However, terrestrial environments show thermal variation to varying degrees in several spatial and temporal levels, including altitudinal (Kuyucu et al, 2018; Lymburner and Blouin-Demers, 2020; Van Damme et al, 1989; Zamora-Camacho et al, 2016), seasonal (Díaz et al, 2006; Huey and Pianka, 1977; Liz et al, 2019; Van Damme et al, 1987) and microhabitat level (Adolph, 1990; Goller et al, 2014; Ortega et al, 2016b; Scheers and Van Damme, 2002). Because of this heterogeneity of the thermal environment, behavioral thermoregulation holds crucial importance for ectothermic organisms including reptiles (Cowles and Bogert, 1944; Huey and Slatkin, 1976; Kearney et al, 2009; McMaster and Downs, 2013; Rangel-Patiño et al, 2020).…”

Thermal biology of two sympatric Lacertid lizards (Lacerta diplochondrodes and Parvilacerta parva) from Western Anatolia

“…Body temperatures of ectotherms, including reptiles, strongly depend on thermal properties of their microhabitats (Goller et al, 2014;Gómez Alés et al, 2017;Huey and Slatkin, 1976;Ortega and Pérez-Mellado, 2016). However, terrestrial environments show thermal variation to varying degrees in several spatial and temporal levels, including altitudinal (Kuyucu et al, 2018;Lymburner and Blouin-Demers, 2020;Van Damme et al, 1989;Zamora-Camacho et al, 2016), seasonal (Díaz et al, 2006;Huey and Pianka, 1977;Liz et al, 2019;Van Damme et al, 1987) and microhabitat level (Adolph, 1990;Goller et al, 2014;Ortega et al, 2016b;Scheers and Van . CC-BY-NC-ND 4.0 International license available under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.…”

“…Because of this heterogeneity of the thermal environment, behavioral thermoregulation holds crucial importance for ectothermic organisms including reptiles (Cowles and Bogert, 1944;Huey and Slatkin, 1976;Kearney et al, 2009;McMaster and Downs, 2013;Rangel-Patiño et al, 2020). The thermoregulatory strategies vary both among and between species, which depends on the costs and benefits of thermoregulation which also depend on several biotic and abiotic factors in the environment Slatkin 1976, Lymburner andBlouin Demers 2020). Species that rely on behavioral thermoregulation can utilize solar radiation by basking (heliothermy) or regulate their heat exchange with the substrate (thigmothermy) (Belliure and Carrascal, 2002;Garrick, 2008;Penniket and Cree, 2015;Rutschmann et al, 2020) to keep their body temperature in set point limits.…”

“…It is shown that even sympatric squamate species that live in the same environments might differ in their usage of thermal micro-habitats (Angilletta, 2009;Gomes et al, 2016;Gómez Alés et al, 2017). Therefore, differentiations in thermoregulatory strategies can also result in alterations for their habitat use in spatial and temporal scales (Buckley et al, 2015;Lymburner and Blouin-Demers, 2020;Neel and McBrayer, 2018;Paterson and Blouin-Demers, 2018). Microhabitat selection (Castilla and Bauwens, 1991;Ortega and Pérez-Mellado, 2016), reproduction activities (Ibargüengoytía et al, 2008;Luo et al, 2010;Meiri et al, 2012;Wang et al, 2016), foraging rates (Kearney et al, 2020;Verwaijen and Van Damme, 2007) and growth patterns (Angilletta et al, 2002;Have and Jong, 1996;Refsnider et al, 2019;Sears et al, 2016) are partly determined by thermal factors in ectotherms' environment.…”