Researchers predict painted turtles face extinction due to global warming

painted turtle
Painted turtle. Credit: US Bureau of Land Management

( —A trio of Iowa State University researchers has predicted, in a paper published in The American Naturalist, that the painted turtle (Chrysemys picta) faces extinction over the next century due to global warming. Research conducted by the team suggests that as the planet warms, painted turtles will begin to produce female-only offspring, leading to gradual extinction of the species.

Painted turtles are the most common species of turtle in North America, and thus are not currently listed as endangered. That will change soon, however, predicts the ISU team, because the gender of their offspring is determined by ambient while the young are still growing inside their eggs. Team member Fredric Janzen has been studying the nesting habits of painted turtles for over 25 years—he's found that painted turtle nesting, like that of many other reptiles, is impacted by how warm or cold it is outside. Warmer temperatures result in more females being born, while colder temperatures result in more males.

Using data from Janzen's research, the new effort entailed creating mathematical models that could predict the gender of painted turtles before they hatched. The team found a success rate of 40 out of 46. Their models show that an average increase in temperature of just 1.1 °C would be enough to cause the turtles to produce all female clutches. The general consensus among Earth scientists is that in North America will increase by approximately 4 °C over the next century, which unless something changes, will spell almost certain for the painted turtle.

Painted turtles are able to adjust the timing of their egg laying, the team notes, by as much as 10 days. If it grows unnaturally warm in the spring, the females will begin laying eggs early. Similarly, if there is a late spring, the turtles can put off laying their eggs a few days in the hopes it will grow warmer. But that won't be enough to prevent all-female in the future, the team says—even if the turtles make simple adaptations, such as laying eggs in the shade—it won't help because it will still be too warm. Painted have long life spans and take a long time to mature and because of that, won't be able to evolve at the pace of global warming, the team says. They will simply run out of time.

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Turtles alter nesting dates due to temperature change

More information: Modeling the Effects of Climate Change–Induced Shifts in Reproductive Phenology on Temperature-Dependent Traits, Rory S. Telemeco, Karen C. Abbott, and Fredric J. Janzen, The American Naturalist, Vol. 181, No. 5 (May 2013), pp. 637-648.

By altering phenology, organisms have the potential to match life-history events with suitable environmental conditions. Because of this, phenological plasticity has been proposed as a mechanism whereby populations might buffer themselves from climate change. We examine the potential buffering power of advancing one aspect of phenology, nesting date, on sex ratio in painted turtles (Chrysemys picta), a species with temperature-dependent sex determination. We developed a modified constant temperature equivalent model that accounts for the effect of the interaction among climate change, oviposition date, and seasonal thermal pattern on temperature during sexual differentiation and thus on offspring sex ratio. Our results suggest that females will not be able to buffer their progeny from the negative consequences of climate change by adjusting nesting date alone. Not only are offspring sex ratios predicted to become 100% female, but our model suggests that many nests will fail. Because the seasonal thermal trends that we consider are experienced by most temperate species, our result that adjusting spring phenology alone will be insufficient to counter the effects of directional climate change may be broadly applicable.

Journal information: American Naturalist

© 2013

Citation: Researchers predict painted turtles face extinction due to global warming (2013, May 6) retrieved 16 September 2019 from
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User comments

May 06, 2013
Oh noooo! NOT DA painted turtle...not da painted turtle. First the Polar Bears now this.
How did they ever survive the MWP. No wait, according to Mann and the AGW Alarmist the MWP never existed.
Just for the record; Cancer still not cured.

May 06, 2013
Seems like alarmist nonsense to me. This is probably on of the most widely distributed turtles in America, ranging from southern Canada all the way down into Mexico. Do they seriously believe that a species that can thrive with temperature fluctuations like those encountered in it's northern range and with the elevated temperatures in it's southern range will be eradicated by a 4 degree rise over the next century? I can imagine that the southern range may lose ground. But beyond that I have no worries for this species, amongst the most common in the US due to it's adaptability.

May 06, 2013
Wikipedia says they've been around for 200 million years, so they have seen dinosaur extinctions, ice ages, continents floating around, the time before the Grand Canyon even existed, and stuff we haven't discovered yet. And now they should all die just because some average temperature slides a tad?

I agree, this has to be alarmist nonsense.

May 06, 2013
I predict universities will go extinct because "researchers" who belong to the AGW cult are dumber than a sack of hammers and not worth a penny of tuition.

May 06, 2013
I wouldn't be surprised at all if the turtles adapt their nesting to compensate for the temp change.

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