One species of turtle may be on the way to extinction as rising global temperatures will prevent the birth of male turtles, according to researchers.
Common in lakes and streams across North America, the painted turtle (Chrysemys picta) is one of many reptiles whose sex is determined by temperature, New Scientist reports. Females tend to hatch in warmer conditions, males in cooler, though why is unknown.
The painted turtle is known to shift their nesting dates to ensure their eggs develop at a temperature that will produce an even mix of males and females.
Iowa State University's Rory Telemeco and his colleague Fredric Janzen have been studying whether climate change could affect the sex ratio of the painted turtles. They used a mathematical model to correctly predict the sex of 40 out of 46 painted turtle hatchlings born in the wild. Applying the same model to predict the sex of future hatchlings, the researchers suggests that future broods would be all females because of rising global temperatures.
The team said average temperatures would only need to rise by 1.1 C before the disappearance of males would be seen.
"The problem is that climate change is happening so rapidly that an evolutionary response, especially in long-lived organisms, is not likely," said Telemeco, according to New Scientist. "It's ultimately extinction."
Richard Shine, an evolutionary biologist at the University of Sydney who was not involved in the research, suggested that the turtles could respond by laying eggs in shadier locations.
But he did note that the effects of rising temperatures would be felt across species.
"All crocodilians, a smattering of turtles and lizards, plus some fishes", will be affected, he said. "Just laying your eggs a few weeks earlier won't be enough to cancel the effects of warming."
The study was published in the American Naturalist.