Condemned to single-sex life by climate change

All tuatara could be born male — and thus doomed to extinction — within decades.

by Narelle Towie

Rising temperatures look set to produce male-only offspring in the tuatara, condemning the ancient reptile species to extinction by 2085, computer modelling predicts.

Researchers studying tuatara (Sphenodon spp.) — the ancient relatives of which once roamed the world alongside dinosaurs more than 200 million years ago — made their doomsday prediction using digital terrain maps detailing the consequences for the reptiles' nesting sites of a 4°C hike in average temperature.


The entire tuatara population is now effectively trapped on about 30 small islands in New Zealand’s north, having been wiped out elsewhere by predators. They therefore have no chance of adapting by fleeing to cooler climes, the researchers say. The study is reported in Proceedings of the Royal Society B1.

“Since the mid 1990s, people have been talking about the vulnerability of reptiles to climate change because they have temperature-dependent sex determination. But no one has been able to model it in this type of complexity before,” says research leader Nicola Mitchell of the University of Western Australia in Perth.

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