Males That Like it Hot

Males That Like it Hot

The Tern
Published: 07/09/2008

By "Tern" Jessica Leber--The tuatara, an ancient reptile in New Zealand, may soon become extinct, according to a new study. The culprit is climate change, but the way in which rising temperatures will kill off these creatures is unusually insidious. By 2085, all tuatara offspring could be male, effectively ensuring this generation is the last in its line, for at least one of the two tuatara species.

In many reptiles, also including most turtles and crocodiles, the sex of a newborn is dependent on the temperature of the egg during development. Only males are born from tuatara eggs raised above 72.05°F, while in nests kept colder than 71.78°F, females dominate (this form of the phenomenon--all males in hotter environments--happens to be uncommon in other reptiles.)

The researchers produced a model that took into account many factors, like climate change, nesting behavior, and topography, to arrive at their prediction of the tuatara's impending sexless demise. It won't even be easy for tuataras to adapt behaviorally to favor females.  For one, they cannot migrate south to cooler climates because they live on small isolated islands (driven there by introduced predators and people). They could theoretically lay their eggs later in the season, but this is unlikely since most egg-laying species are nesting earlier as it gets warmer. Possibly their best hope, save a halt to global warming, is for us to relocate them somewhere more suitable.

All of this is rather unfortunate because tuataras happen to be pretty cool reptiles. They evolved more than 200 million years ago and roamed with the dinosaurs. Though these two-foot long spiny "living fossils" look like lizards, their closest relatives are long extinct.  They have a third eye on top of their head and are a rare example of a species that's both cold-blooded and nocturnal. It would be a shame to lose them, Dr. Michael Kearney, one of the study's co-authors, told The Daily Mail.