Temperature and oxygen availability interact to shape nearly every aspect of ectotherm biology, from blood biochemistry to metabolic capacity to whole-organism performance. To test the relative roles of local adaptation and within-individual plasticity in response to reduced oxygen availability in shaping the multivariate thermal and metabolic phenotype, we performed a transplant experiment with the upslope-colonizing common wall lizard (Podarcis muralis). First, we measured nine aspects of thermal physiology and aerobic capacity in lizards from replicate low elevation (400 m above sea level) and high-elevation (1700 m ASL) populations at their native elevation. We then transplanted half of each group to extreme high elevation (2900 m ASL), where oxygen availability is reduced by ~25% relative to low elevation sites. After three weeks of acclimation, we again measured these traits and identified multiple phenotypic shifts. Traits relating to long-term aerobic capacity, including blood haemoglobin concentration and running endurance capacity, demonstrated acclimation to both captivity and reduced oxygen availability. Upper and lower critical thermal limits, resting metabolic rate, and maximal metabolic rate did not demonstrate a strong plastic response, but did segregate between lizards from low- and high-elevation populations, suggesting these traits may be locally adapted. By identifying axes of covarying traits that may shift via within-individual plasticity or as a result of selection, we can better characterize potential restraints on organismal response to novel thermal and oxygen environments.