From Mother Nature Network's Russell McLendon:

If you're a male painted turtle, global warming might sound great at first: A new study suggests it will mean more females to mate with and fewer male rivals to fend off.

But, as usual with climate change, every silver lining has a cloud. In this case, too many females could render the species incapable of reproducing by century's end.

Painted turtles (Chrysemys picta) live in freshwater habitats across North America, where the sex of their unhatched young is determined by ambient temperature. Cooler weather favors male babies; warmth leads to more females. The reason for this remains unclear, but it's a trait shared by many reptile species as well as certain types of fish.

Mother turtles have some control over the phenomenon, shifting their nesting dates by up to 10 days in an apparent attempt to balance their offspring's sex ratio. Researchers from Iowa State University discovered this by studying painted turtles on a small island in the Mississippi River for 25 years. But in a new study, the researchers conclude that not even 10 days of wiggle room are enough to offset the effects of climate change.

"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," the researchers write. "Not only are offspring sex ratios predicted to become 100 percent female, but our model suggests that many nests will fail."

A temperature rise of just 1.1 degrees Celsius (1.98 Fahrenheit) could trigger all-female nests, the researchers report, even if mother turtles lay eggs earlier. And since average global temperatures are projected to rise by 4 to 6 degrees Celsius (7.2 to 10.8 Fahrenheit) in the next 100 years, the researchers say extinction is a possibility — even though painted turtles overall are not yet considered an endangered species.

The turtles could still find ways to dodge an all-female future, such as by choosing shadier nesting sites or evolving less heat-sensitive eggs. But as lead author Rory Telemeco tells New Scientist, the speed of climate change makes such adaptations difficult.

"The problem is that climate change is happening so rapidly that an evolutionary response, especially in long-lived organisms, is not likely," he says.

Although their study focuses on painted turtles, the researchers add that a variety of wildlife may be vulnerable to shifting sex ratios. "Because the seasonal thermal trends that we consider are experienced by most temperate species," they write in the journal American Naturalist, "our result that adjusting spring phenology alone will be insufficient to counter the effects of directional climate change may be broadly applicable."

That might not be the only broadly applicable lesson we can learn from painted turtles, though. Scientists recently sequenced the species' genome, part of an effort to learn how it performs feats like hibernating underwater or surviving for months with little oxygen. Aside from possibly yielding new medical treatments for humans, painted turtles' genes may also offer clues about how they — and other animals — will respond to climate change.

"Turtles have repurposed some of the genes that they share with their relatives, but they’ve tweaked them and gotten some innovative outcomes," says Fredric Janzen, an evolutionary biologist at Iowa State who contributed to both studies.

Related on HuffPost:

Loading Slideshow...
  • Angler Fish: Just A Little Clingy

    The next time you think your mate is getting a little too attached, just be glad you're not an <a href="http://www.bbc.co.uk/dna/h2g2/A22547838" target="_hplink">angler fish</a>. According to an h2g2 post, when a male angler fish finds a mate, he clings on for dear life. Perhaps because the angler fish is so horrifyingly unattractive, he feels that any less drastic measure would surely lose her. Thus, he bites into her, attaching himself permanently, linking his blood supply to hers. While she provides nourishment to him, he offers her sperm whenever there are eggs to fertilize. Fair trade-off?

  • Octopuses: A Man's Greatest Fear

    A man's greatest fear? Discovery Science reports that in the <a href="http://science.discovery.com/top-ten/2009/mating-ritual/mating-ritual-01.html" target="_hplink">octopus</a> world, it's actually expected that a male's penis will break off during mating. Fortunately, it grows back in time for the next mating season.

  • Hippos: Where Poop Is A Turn On

    There may have been a "Jerry Springer" episode about this... A male <a href="http://science.discovery.com/top-ten/2009/mating-ritual/mating-ritual-10.html" target="_hplink">hippopotamus</a> attracts a female by spraying her with his feces, Discovery Science reports. And who says bathroom talk isn't sexy?

  • Flamingos: Just A Touch Of Makeup

    Flamingos may use pigments from gland secretions to improve the color of their feathers, thus attracting better mates. A <a href="http://www.sciencecentric.com/news/10102624-beauty-from-the-bottom-up.html" target="_hplink">study</a> from the Estacion Biologica de Donana in Spain found that there was no particular reason for flamingos to alter their colors, except for mating purposes. L'Oreal and Maybelline should look into this new potential client base.

  • Midges: It Sucks

    A <a href="http://science.discovery.com/top-ten/2009/mating-ritual/mating-ritual-08.html" target="_hplink">midge</a> engages in intercourse by sucking out the male's bodily fluids. Enough said.

  • Garter Snakes: One Big Orgy

    For the<a href="http://www.neatorama.com/2007/04/30/30-strangest-animal-mating-habits/" target="_hplink"> Red-Sided Garter Snake</a>, orgies aren't just a fantasy, they're very much a reality. But men, don't get too excited yet. According to Neatorama, it's the females who have sex with hundreds of partners during the mating season. The snake ladies release a pherome to attract the men and quickly a "mating ball" forms, which is, just as the name implies, a big ball of snakes trying to mate.

  • Porcupines: It's No Hazing Ritual

    This <a href="http://science.discovery.com/top-ten/2009/mating-ritual/mating-ritual-02.html" target="_hplink">porcupine</a> mating ritual could easily be confused for a fraternity hazing ritual. But, according to Discovery Science, a male porcupine will shower a female with his urine before mating, and there's no keg stand involved.

  • Horseshoe Crabs: If You Like Long Walks On The Beach...

    It's like an ad in the personal columns: "seeking mate for summertime romance on the beach under a full moon." Except that for <a href="http://www.wired.com/wiredscience/2009/02/animalcourting/" target="_hplink">horseshoe crabs</a>, this isn't romantic, it's just their regular mating ritual, WIRED reports. This anthropod only mates under these seemingly idyllic circumstances.

  • Elephants: Keeping Romance Alive

    Who said chivalry was dead? The male <a href="http://www.wired.com/wiredscience/2009/02/animalcourting/" target="_hplink">elephant</a> takes his time to woo a female, courting her over a period of weeks before mating. While flowers and chocolate aren't included, the male does bring the female food and squirt her with water.

  • Mosquitoes: A Little Love Song

    Who knew such an obnoxious insect could be so very romantic with its own species? <a href="http://www.wired.com/wiredscience/2009/02/animalcourting/" target="_hplink">Mosquitoes</a> flap their little wings, producing various sound frequencies (or to us, an annoying buzz). While the male normally produces a sound around 600 hertz, the female makes a 400 hertz sound. But compromise is key with these buggers. Both sexes are willing to adjust their sound level to create a harmonic match.

  • Snakes: Like A Magic Trick, Only Better

    According to a BBC article, not only does a <a href="http://www.bbc.co.uk/dna/h2g2/A22547838" target="_hplink">snake</a> have <em>two</em> intromittent organs, but it also has the ability to turn its penis inside-out to better fit the female.

  • Dolphins: A Gay-Friendly Community

    <a href="http://www.bbc.co.uk/dna/h2g2/A22547838" target="_hplink">Dolphins</a> are quite a progressive species. Not only are they considered one of the most intelligent animals, but according to h2g2, dolphins also engage in openly gay sex. Male dolphins have been known to practice various forms of intercourse with other males, experimenting with different holes.

  • Ducks: This Is Just Bad

    Apparently some animal species don't find rape quite as abhorrent as we do. The male <a href="http://www.bbc.co.uk/dna/h2g2/A22547838" target="_hplink">duck</a>, also known as a drake, has a phallus so large that it can be the length of the drake himself, according to an h2g2 post. Due to his size, the drake can have sex with a female without her consent. It is not uncommon for a group of drakes to force a female to have sex, occasionally even drowning her. But the female duck has some defense mechanisms. She has the ability to store sperm in a side chamber and eject it if she is unsatisfied. It is thought that female ducks have evolved to create a complex genital passage due to the threat of unwanted sex.

  • Bowerbird: Not Just a Bachelor-pad

    The male <a href="http://www.nileguide.com/blog/2010/03/10/the-most-ridiculous-animal-mating-rituals/" target="_hplink">bowerbird</a> doesn't settle for just any old bachelor-pad to woo his mate. Instead, NileGuide reports that he takes the time to decorate his nest, collecting feathers, flowers, berries, and shells to beautify his home and woo female Bowerbirds during mating season. The female Bowerbird chooses the nest that she likes best, and settles in with a male for the season. Perhaps men <em>should</em> spend a little more time decorating their apartments.

  • Cats: The Horror

    It may sound like an erotic horror film, but a male <a href="http://www.bbc.co.uk/dna/h2g2/A22547838" target="_hplink">cat</a> has hook-like barbs on his penis, h2g2 reports. During intercourse, the penis cuts the female, encouraging her to ovulate.