Climate change could devastate painted turtles, according to new study

March 12, 2019, Iowa State University

Climate change threatens the painted turtle, a species that undergoes temperature-dependent sex determination. Research led by Nicole Valenzuela indicates that warming temperatures, as well as wider fluctuations in temperature, could lead …more

An Iowa State University biologist is sounding the alarm for the painted turtle, one of many reptiles for which climate change could prove particularly threatening.

Fluctuations in temperature driven by climate change could devastate a range of species for which sex is determined by temperature during critical stages of development, according to recently published research led by Nicole Valenzuela, a professor of ecology, evolution and organismal biology. Rising temperatures, along with wider oscillations in temperature, could disrupt the ratio of males to females in painted turtle populations and threaten the survival of the species, Valenzuela said. The study was published in the peer-reviewed journal Scientific Reports.

Painted turtles undergo temperature-dependent sex determination while developing inside the egg. Eggs exposed to warmer temperatures tend to produce females, while cooler temperatures tend to produce males, Valenzuela said. Numerous turtle species – as well as crocodilians, some lizards and the tuatara – undergo temperature-dependent sex determination. And increasing average temperatures combined with stronger thermal fluctuations that result from climate change could lead to drastic shifts in the demographics of those species, she said, eventually leading to population collapse and possibly extinction.

Valenzuela and her coauthors exposed eggs from Iowa to temperatures recorded in nests from three different painted turtle populations in Iowa, Nebraska and Canada from which the proportion of males and females was also recorded. Valenzuela said that allowed the experiments to compare the responses of multiple painted turtle populations, which revealed that not all populations exhibit the same sensitivity to temperature.

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