1C Increase In Temps Guarantees Extinction For Painted Turtles; Would Become All-Female - N.S.

[hatrack]

Males don't stand a chance in a warmer world, if they happen to be painted turtles. A temperature rise of around 1 °C is all it would take for the species to become 100 per cent female and earmarked for extinction.

Painted turtles (Chrysemys picta), found in lakes and streams across North America, are one of many reptile species whose sex is determined by temperature. Eggs in warm nests are likely to hatch as females, while males hatch in cooler nests, although no one is sure why. In recent years, many researchers have raised concerns that global warming could skew the sex ratios of these reptiles. Rory Telemeco and his colleagues at Iowa State University developed a mathematical model to predict whether the painted turtles might be affected.

For over 25 years, Telemeco's colleague, Fredric Janzen, documented the nesting times and sex ratio of painted turtle hatchlings on a small island in the Mississippi river in Carroll County, Illinois. He found that females can shift their nesting dates by about 10 days to ensure their eggs develop at temperatures that produce an even mix of males and females.

EDIT

Telemeco's team then used the same model to predict what might happen to the sex ratio of future hatchlings. Conservative climate models predict that average temperatures in the US Midwest will rise by 4 °C over the next century. The group's model suggests that this temperature hike would result in nests of all-female hatchlings, even if the turtles nest earlier, when temperatures are cooler. In fact, average temperatures only need to rise by 1.1 °C to have this effect, the team found. "It's ultimately extinction," says Telemeco. Richard Shine, an evolutionary biologist at the University of Sydney in Australia, who was not involved in the study, says the findings are likely to apply to many species where sex is dependent on temperature. "All crocodilians, a smattering of turtles and lizards, plus some fishes", will be affected, he says. "Just laying your eggs a few weeks earlier won't be enough to cancel the effects of warming," he says.

EDIT

http://www.newscientist.com/article/dn23486-painted-turtles-set-to-become-allfemale.html

[CRH]

1. Actually 1*C almost certainly guarantees human extinction, ...

At just .8*C the planet climate system's heat pump has been engaged, positive feedbacks are flawlessly functioning, methane release from failing frozen carbon sinks are guaranteeing more of the same; and all of the above are irreversible in human time frames.

The sex ratio of turtles might seem trivial, but it is just a symptom of much worse times to come for most life on the planet. Not a question of if, only when.