The Nature Center’s painted turtle, Chrysemys picta, is a native species that may encounter reproduction problems from increasingly warmer temperatures and sharp temperature swings introduced by climate change. Like a number of turtle species, along with crocodilians, some lizards, and the tuatara, painted turtle embryos undergo temperature-dependent sex determination during development inside the egg. Warmer temperatures tend to produce females while cooler readings bring forth males.

Researchers at Iowa State University exposed C. picta eggs to temperature fluctuations mimicking conditions in nature as well as to conditions where oscillations were exaggerated to mimic climate change scenarios. While higher temperatures continued to produce females, cooler temperatures, expected to produce males, under the influence of intensive heat fluctuations, also produced females. Embryos from warmer profiles remained female or died when the fluctuations intensified.

“The greater temperature oscillations associated with climate change add to the effect of just higher average temperatures,” noted the research director Nicole Valenzuela. “If an average increase in temperature is accompanied by greater variance, we’ll see populations becoming unisexual faster than anticipated. The greater oscillations add to the effect of just higher average temperature.” Valenzuela said the loss of habitat and exploitation has already left many turtles vulnerable to extinction, and climate change only adds to the peril these species face.