Thursday, October 18, 2012

A dinosaur extinction... again?

The tuatara is a reptile native to New Zealand that has been around for a very, very long time. It's most closely related to species that last existed during the mesozoic period. It has outlasted its relatives through the extinction of the dinosaurs, ice ages, humans, and more. But now, after all this time, biologists are concerned that the tuataras might soon cease to exist.

What has led to the tuatara's success over the last 230 million years? It turns out that they are able to be active at much lower temperatures than other reptiles, down to 7 degrees Celsius (44 Fahrenheit). This allows them to do their hunting at night, giving them access to food and resources that other reptiles cannot access. However, the tuatara can't compete with introduced nocturnal species such as dogs and rats, which have driven them off of mainland New Zealand to small offshore islands where they receive government protection.

So what is threatening the tuataras on these islands? The answer is climate change. Temperature determines whether a tuatara egg is more likely to be male or female. Warmer temperatures are now causing too many eggs to develop into males. At extremes all eggs develop into one gender. A climactic model suggests that by 2085 tuataras will be producing 0 females. Efforts are now being made to move tuataras to colder parts of New Zealand.

If the tuataras were not confined to such small islands, they could move to warmer or coolers areas to adjust to climate change. However, introduced species have destroyed this possibility for them. Read more about the tuatara at NPR.

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