“…There are fewer species adapted to live in thermally challenging environments (Blouin‐Demers & Weatherhead, 2001; Herczeg, 2006; Besson & Cree, 2010; Lourdais et al ., 2013; Bouazza et al ., 2016; Ortega et al ., 2016). Previous studies on lizard thermoregulation across elevational gradients have indicated that T b decreases (Diaz de la Vega‐Pérez et al ., 2019; Gilbert & Miles, 2019; Senior et al ., 2019) or remains unchanged (Burns, 1970; Zamora‐Camacho, Reguera & Moreno‐Rueda, 2016) with elevation despite the decrease in ambient temperature, but these studies were conducted on few populations or across narrow elevational gradients, thus limiting inferential power and representativity. Behavioural thermoregulation in harsh environments, although costly, may be required to buffer against the impact of temperature variation (Huey, Hertz & Sinervo, 2003; Basson et al ., 2016) and extreme temperatures (Vickers et al ., 2011; Woods, Dillon & Pincebourde, 2015) on performance, but to further our understanding of how investment in thermoregulation changes with thermal quality, we must look at several populations facing a gradient of thermal environments.…”