Refuge Use in a Patagonian Nocturnal Lizard, Homonota darwini: The Role of Temperature

Performance and thermal sensitivity of the southernmost lizards in the world, Liolaemus sarmientoi and Liolaemus magellanicus

“…However, at low temperatures greater speed in sprint than in long runs shows that L. sarmientoi and L. magellanicus prefer short distances instead of long ones to capture prey, escape from predators, and for many other potential social activities when temperature is a limited resource. This is also the case for the nocturnal gecko Homonota darwini, partially sympatric in its southernmost distribution, which has an optimum adaptation in locomotion to the nocturnal conditions of activity, for sprints only (Aguilar and Cruz, 2010;Ibargüengoytía et al, 2007).…”

Running in cold weather: morphology, thermal biology, and performance in the southernmost lizard clade in the world (Liolaemus lineomaculatussection: Liolaemini: Iguania)

“…To measure sprint speed, we used a 1.2‐m long racetrack with seven LED sensors and beams (spaced every 0.155 m) connected to an electronic circuit, and hooked up to a computer. Lizards were forced to run by gently tapping them on the base of their tail (Angilletta et al, 2002; Aguilar and Cruz, 2010). The racetrack surface was covered with cork to provide traction.…”

Warmer isn't always better: Performance eurythermy in a cold‐climate gecko

“…Because these geckos spend a significant amount of time thermoregulating inside shelters by day and foraging in the open at night (Aguilar & Cruz, 2010; Ibargüengoytía et al, 2007), we placed miniature temperature loggers (±0.5°C; iButton DS1922L; Thermocron, Lawrenceburg, KY) in known gecko shelters, such as under rocks ( N = 2), and in the open at the base of small shrubs near known gecko shelters ( N = 2) at each of the four field sites. Although the small number of loggers deployed at each site may pose some inferential limitations, we expected the within‐site variation in microclimates recorded by the loggers to be smaller than the among‐site variation given the substantial distances and latitudinal, elevational, and habitat differences among the sites.…”

“…They are characterized as saxicolous and use flat rocks as diurnal shelters (Ibargüengoytía et al, 2007), but they may also occupy other shelters including surface litter and rodent burrows. During the activity season (October–March) they are typically encountered on the ground or near shelters from twilight until a few hours before sunrise (Aguilar & Cruz, 2010; personal observation). Like most of the world's nearly 1,900 species of geckos (Uetz, Freed, & Hošek, 2019), H. darwinii are nocturnal, yet unlike H. darwinii , most other gecko species live in warm tropical climates (Bauer, 2013; Pianka & Vitt, 2003) where maintaining relatively high T b s—even at night—is less of a problem.…”

“…In their study of H. darwinii from San Carlos de Bariloche, Río Negro, Argentina (41.08 °S, 71.13 °W; 800 m), Ibargüengoytía et al (2007) compared diurnal to nocturnal temperature‐dependent performance and concluded that although the low T b s this population routinely experiences during activity are suboptimal for sprinting, the geckos compensate by sprinting over short distances. In a second study, Aguilar and Cruz (2010) investigated the thermal preferences of H. darwinii collected just 2 km away (41.10 °S, 71.13 °W; 900 m) from the study site used by Ibargüengoytía et al (2007). Geckos from this site experienced lower mean T b in diurnal shelters (21.5°C) relative to their preferred diurnal T b in a laboratory gradient ( T pref = 27.4°C) from February through March (late summer to early fall).…”