Sluggish tuatara fastest in DNA evolution

From The New Zealand Herald
4 March, 2008

By  Angela Gregory

They are slow to grow, slow to reproduce and have a sluggish metabolism.  But tuatara have broken records for DNA evolution, a discovery that has astonished New Zealand scientists.

Tuatara, often referred to as living dinosaurs, have largely not changed physically over very long periods of evolution going back millions of years.  But analysis of their old bones in New Zealand has shown that their DNA has evolved faster than any other animal species yet studied.

Evolutionary biologist Professor David Lambert, of Massey University, and a team from the Massey-based Allan Wilson Centre for Molecular Ecology and Evolution established through study of tuatara DNA that the reptiles evolved very quickly.

Professor Lambert told the Herald yesterday it had been expected that the tuatara, which did everything slowly, would have therefore evolved slowly.  But the new DNA research questioned such notions.

The scientists recovered DNA sequences from the bones of tuatara up to 8750 years old and compared them to blood samples of modern day tuatara to establish the speed of the DNA changes.

Professor Lambert said the tuatara rate was significantly faster than for animals such as the cave bear, lion, ox and horse.

"What we found is that the tuatara has the highest molecular evolutionary rate that anyone has measured."

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