A key aim of ecology is understanding how populations respond to environmental variation, especially rapid climate warming. While climate change is typically modeled on a continental or global scale, responses depend on complex physiology-microenvironment interactions that manifest at both population and individual levels. In species with temperature-dependent sex determination (TSD), temperature variation may dramatically skew offspring sex ratios, reducing population viability. However, predictive models that rely on broad-scale climate data do not capture the microclimate-scale processes that drive thermally-mediated embryonic development and sexual differentiation. We used a spatially-explicit model of embryonic development, driven by NicheMapR, a mechanistic soil temperature model, to examine the microclimate-mediated consequences of potential behavioral and physiological responses to climate warming in painted turtles (Chrysemys picta), a widespread model species with TSD.
Shifts in thermal reaction norms, due to modifications of either maternal behavior (nesting phenology and/or nest location and depth) or temperature-dependent developmental parameters, could buffer offspring sex ratios against climate change. However, effectiveness of either a strategy is mediated locally by the rate of response(s) and magnitude of climate warming observed. Our findings highlight the importance of using spatially explicit data to quantifying the thermal suitability of nesting sites for incubation and sex determination for C. picta and other species with strictly, thermally-mediated physiological traits. In addition, our results highlight the importance of defining habitat suitability at multiple scales. The effects of environmental variation, particularly rapid climate change, may vary for distinct life stages and at individual vs. population levels.