Warming May Drive Tuatara Extinct

From National Geographic News.

Less than one degree Celsius (1.8 degrees Fahrenheit) is all that stands between the tuatara—New Zealand's "living fossil" reptile—and extinction, scientists say.

The sex of tuatara—the sole surviving species of an ancient family of reptiles dating back 200 million years—is determined by the incubation temperature of its eggs. As the mercury climbs, so does the proportion of male hatchlings.

The mechanism is so delicate that a flagging population on remote North Brother Island in Cook Strait is already running short of breeding females.

"At 22 degrees Celsius [71.6 degrees Fahrenheit], we got 100 percent males. At 21 degrees Celsius [69.8 degrees Fahrenheit], we got three males out of 80 eggs," Nelson said.

Intensifying the problem is the slow reproduction rate of the reptiles. On average, female tuatara mate once every four years, and eggs take between 11 and 16 months to hatch.

"These creatures can live for more than a hundred years. We're talking perhaps a 5-degree jump in a single animal's lifetime," Nelson said.

"We're not talking adaptation—we're talking about the abilities of individuals to survive."

So scientists are gathering eggs from North Brother and from nearby Takapourewa, or Stephens Island, and raising them in artificial incubators.

"We can dial in whichever sex we like," Nelson said.

Saving the tuatara is a matter of pride among New Zealand's indigenous groups. The animals are revered by the Maori as a taonga, or treasure.

"In the Maori worldview we believe that everything is connected, so that tuatara are part of our whakapapa—our genealogy," Paine added.

"We are kaitiaki—guardians—of those tuatara, so we have an obligation from our ancestors to ensure their well-being, to make sure they're protected. To lose them would be like losing part of ourselves."


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