Higher Body Temperatures and Earlier Parturition in Response to Hypoxia Experienced by Pregnant Lizards

Many species are shifting towards higher altitudes in response to global wa rming, but how these upslope-shifting species will respond to hypoxic environments at high altitudes remains unclear. Hypoxia can be especially challenging for viviparous reproduction because of the limitation of oxygen supply to the female and her developing embryos. To investigate the effect of hypoxia on viviparous females and their offspring we acclimated pregnant females of a high-altitude dwelling vivipa rous liza rd(Phr ynocephalus vlangalii) to local oxygen and hypoxia conditions, respectively. We then recorded maternal body temperatures, postpartum body condition, as well as offspring morphology and locomotor performance. We found that pregnant females had higher body temperatures and advanced their parturition under hypoxic acclimation. However, maternal body condition, offspring morphology and locomotor performance were unaffected by the hypoxic conditions during gestation. Our study suggests that upslope-shifting viviparous lizards respond to hypoxic environments by plastically adjusting their body tempera tures to reduce parturition time, without short-term costs to offspring traits.