Data from: Effects of hypoxia on the thermal physiology of a high-elevation lizard: Implications for upslope-shifting species

Montane reptiles are predicted to move to higher elevations in response to
climate warming. However, whether upwards-shifting reptiles will be
physiologically constrained by hypoxia at higher elevations remains
unknown. We investigated the effects of hypoxic conditions on preferred
body temperatures (Tpref) and thermal tolerance capacity of a montane
lizard (Phrynocephalus vlangalii) from two populations on the
Qinghai-Tibet Plateau. Lizards from 2600 m asl were exposed to O2 levels
mimicking those at 2600 m (control) and 3600 m (hypoxia treatment).
Lizards from 3600 m asl were exposed to O2 levels mimicking those at 3600
m (control) and 4600 m (hypoxia treatment). The Tpref did not differ
between the control and hypoxia treatments in lizards from 2600 m.
However, lizards from 3600 m selected lower body temperatures when exposed
to the hypoxia treatment mimicking the O2 level at 4600 m. Additionally,
the hypoxia treatment induced lower critical thermal minimum (CTmin) in
lizards from both populations, but did not affect critical thermal maximum
(CTmax) in either population. Our results imply that upwards-shifting
reptiles may be constrained by hypoxia if a decrease in Tpref reduces
thermally-dependent fitness traits, despite no observed effect on their
heat tolerance.