Are the Kids Alright? Dehydration and High Temperatures During Pregnancy Impact Offspring Physiology, Morphology, and Survival in a Cold-adapted Lizard

Climate change will continue to increase mean global temperatures, with daily minima increasing more than daily maxima temperatures on average. In addition, altered rainfall patterns due to climate change will disrupt water availability. Such changes are likely to influence thermo-hydroregulation and reproduction strategies in terrestrial ectotherms. We manipulated access to preferred diurnal temperature (9 h vs. 4 h at preferred temperature), nocturnal temperature at rest (22 vs. 17°C) as well as water availability during gestation (± ad libitum access to water) in female common lizards (Zootoca vivipara), a cold- and wet-adapted species. We previously reported that hot conditions (day and night) accelerated gestation but high nighttime temperatures increased the burden on females already constrained by heavy resource and water investment during gestation. We expanded the understanding of this relationship by examining the effects of maternal hydration and temperature on offspring (neonates and juveniles; N = 625) physiology (water loss rates and respiratory activity), morphology, performance (endurance capacity and growth), and survival. On average, longer access to preferred temperature during the day conferred benefits on offspring growth and survival, despite a negative effect on body condition at birth. High nighttime temperatures during gestation reduced offspring postnatal growth during early life and, together with high daytime temperatures, reduced tail width and endurance capacity at birth as well as offspring survival. Additionally, water deprivation poses a challenge to homeostasis, but offspring demonstrate resilience in coping with this potential stressor and these effects were not stronger in hot climates. Notably, the benefits of hotter environments are not always additive, highlighting the complexity of temperature-mediated effects on maternal and offspring outcomes.