RESUMEN
Across the globe terrestrial ectotherms-amphibians and non-avian reptiles-are facing a range of emerging challenges. Increasing global temperatures, in particular, are affecting all aspects of ectotherm biology and life history. Embryonic development is a thermally sensitive period of the organismal lifecycle, yet the impacts of thermal stress on the early development of ectotherms have significantly lagged behind studies of later stages and adult thermal physiology. Morphogenesis, the stage where the major anatomical systems are actively forming, is particularly sensitive to thermal stress, yet is not studied as often as later stages where growth is the primary process happening within the egg. Here, we focus on the effects of thermal stress on the first 12 days of development, the stages of morphogenesis, in the lizard Anolis sagrei. We examine the resiliency of the early developmental stages to heat stress by incubating eggs at temperatures that parallel conditions observed today and predicted over the next 50-100 years of projected climate change. Our results suggest that some anole nests are currently at the thermal limits for which the early embryonic stages can properly develop. Our results emphasize the importance of studying early embryonic stages of development and the importance of studying stage-specific effects of thermal stress on squamate development.