Species with large geographic ranges provide an excellent model of how different populations respond to dissimilar local conditions, particularly variation in climate. Maternal effects, such as oviposition-site choice greatly affect offspring phenotypes and survival. Thus, maternal behavior has the potential to mitigate the effects of divergent climatic conditions across a species’ range. We delineated natural nesting areas of six populations of painted turtles (Chrysemys picta) that span a broad latitudinal range and quantified spatial and temporal variation in nest characteristics. To quantify microhabitats available for females to choose, we also identified sites within the nesting area of each location that were representative of available thermal microhabitats. Across the range females nested non-randomly and targeted microhabitats that generally had less canopy cover and thus higher nest temperatures. Nest microhabitats differed among locations but did not predictably vary with latitude or historic mean air temperature during embryonic development. In conjunction with other studies of these populations, nest-site choice appears to be homogenizing nest environments, buffering embryos from thermally-induced selection, which could stymie evolution of embryonic traits. Thus, although effective at a macroclimatic scale, nest-site choice may be unable to compensate for novel stressors that rapidly increase local temperatures.

The processed data included: the Constant Temperature Equivalents created by using the models available from Telemeco, Abbott, & Janzen (2013) Am.Nat. in MATLAB, the approximate mean, maximum, and minimum temperatures for natural nest sites and representative nest sites, and the processed hemispherical photos (Gap Light Analyzer) outputs as % canopy open.