Thermoregulation in a cold-adapted species (Cyren’s Rock Lizard, Iberolacerta cyreni): influence of thermal environment and associated costs

Abstract

Thermal constraints may limit the physiology and behaviour of ectotherms because of the high thermal dependence of metabolic functions. The adaptive mechanisms of thermoregulation and the cost of confronting thermal constraints were studied in the Cyren’s Rock Lizard (Iberolacerta cyreni (Müller and Hellmich, 1937)), a lacertid lizard endemic to mountain areas of central Spain. Semicontinuous monitoring of body temperature (Tb) in the laboratory indicated that the preferred temperature range for this population (Tpref) was lower than those found for most lacertid lizards, and field body temperatures of active animals in summer were even lower than Tpref. Overall these results, together with distribution of field operative temperatures (Te), indicate that I. cyreni is an active and relatively accurate thermoregulator, although limited by thermal constraints in their habitat. Laboratory experiments in contrasting thermal environments showed that even under thermally restricted conditions, lizards achieved their Tpref by modifying their thermoregulatory behaviour, principally through changes in space use, basking time, and body posture. However, these behavioural adjustments to reach the Tpref have associated costs, and lizards spent 80% of their time in thermoregulation when tested under low radiation conditions, which in the wild would limit the scope for other activities and eventually increase predation risk. Our results suggest that thermoregulatory behaviour may play an important role in coping with global climate change, hence predictions of the effects of climate warming on lizards inhabiting cold habitats should take into account the buffering role of behavioural thermoregulation.

Researching functional ecology in Kosciuszko National Park

“…This supports the hypothesis that alpine lizards may benefit from short-term warming, and agrees with past research (Aguado and Braña 2014;Caldwell et al 2015). Nevertheless, several limitations must be noted.…”

“…Indeed, recent analyses suggest that tropical lizards are more in danger of extinction due to climate warming (Sinervo et al 2010) than temperate and alpine lizards (Aguado and Braña 2014;Caldwell et al 2015). Nevertheless, thermal performance curves vary between species, and whether all temperate lizards benefit from short-term climate warming remains unclear (reviewed in Clusella-Trullas and Chown 2014).…”

Heat tolerance is more variable than cold tolerance across species of Iberian lizards after controlling for intraspecific variation

“…For instance, lizard cold tolerance can be adjusted to nocturnal temperatures but thermoregulation should play no role in such adjustments and only limit exposure to diurnal temperatures approaching the limits of heat tolerance for diurnal species (Domínguez–Guerrero et al, ; Muñoz & Bodensteiner, ). Consequently, complex biogeographic patterns of variation in heat and cold tolerance could emerge regionally depending on the opportunities for effective thermoregulation, the prevalence of which could prevent microevolutionary adaptation despite its potential to buffer lizards against heat stress in regions such as the Iberian Peninsula (Aguado & Braña, ; Ortega, Mencía, & Pérez‐Mellado, 2016a).…”

Life-History Responses to the Altitudinal Gradient

“…Temperature increases may not necessarily have the expected worst impact on ectotherm metabolism because they may adjust thermoregulation and activity to prevailing temperatures (Aguado and Braña 2014), as alpine plants do with respiration (Larigauderie and Körner 1995). It is also worth stressing that warming reduces some of those constraints dominating alpine life, as evidenced by improved survival or reproductive output of a number of species (e.g.…”