Linking climate and physiology at the population level for a key life-history stage of turtles

Forthcoming climate change is expected to impact the global biota, particularly by altering range limits. However, the roles of early life stages in affecting biogeography and the impact of climate change on reptiles are both poorly understood. Fitness of neonatal reptiles depends greatly on energy reserves and body size, which themselves are affected by abiotic conditions in laboratory experiments performed during embryonic development and posthatching dormancy. To test whether these relationships between environment and physiology hold in nature, we conducted a 6-year field study on a natural northern population of red-eared slider turtles, Trachemys scripta elegans (Wied-Neuwied, 1839). Climatic conditions varied substantially and impacted offspring phenotypes. Consistent with bioenergetic predictions, cohorts that experienced warmer periods of posthatching dormancy had less dry residual yolk mass than similar-sized hatchlings that experienced cooler overwintering periods. Thus, global warming may exert adverse effects on turtle energy reserves important to fitness during crucial early life stages; this negative physiological impact may extend to other ectotherms with obligate, nonfeeding stages.