for National Geographic News
New Zealand's "living dinosaur," the tuatara, hasn't changed its look in millions of years. But the reptile is actually evolving faster than any other animal studied so far, new DNA analysis reveals.
Scientists recovered DNA from 8,000-year-old tuatara bones and compared it with DNA in blood samples from living tuatara. The modern species is the only surviving member of the order Sphenodontia, which flourished around 200 million years ago.
The results showed that tuatara evolve faster than bears, horses, and many other warm-blooded vertebrates.
(Related: "'Instant' Evolution Seen in Darwin's Finches, Study Says" [July 14, 2006].)
"Tuatara do most things slowly," said study lead author David Lambert of New Zealand's Massey University. He and colleagues published the findings in the March issue of the journal Trends in Genetics.
Tuatara "have a very low metabolic rate. So you would be forgiven for thinking that they haven't been doing very much over 200 million years of evolution."
But Lambert said the reptile's ancient anatomy hides the rapid evolution of DNA within the animals' cells.
"What [the research] is telling us is that the processes that govern anatomical evolution are quite different from those governing molecular evolution."
Axel Meyer, of the University of Konstanz in Germany, agreed.
"There can be a real disconnect" between an animal's physical and genetic evolution rates, said Meyer, who was not involved in the research.
"Fast [evolution] does not necessarily imply 'good' or 'adaptive,'" he added.
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