KEY POINTS:
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."
Professor Lambert said the research has been published in the latest issue of the international journal Trends in Genetics and features on its cover.
"We've been swamped with interest from all over the world."
He said the new research supported a hypothesis by the evolutionary biologist Allan Wilson, a New Zealander, that the rate of molecular evolution was uncoupled from the rate of morphological evolution.
"Allan Wilson, who died of leukaemia in 1991, was a pioneer of molecular evolution. His ideas were controversial when introduced 40 years ago, but this new research supports them."
Professor Lambert said the finding would be helpful in terms of future study and conservation of the tuatara, and the team now hoped to extend the work to look at the evolution of other animal species after studying about a dozen so far.
"We want to go on and measure the rate of molecular evolution for humans, as well as doing more work with moa and Antarctic fish, to see if rates of DNA change are uncoupled in these species."
Professor Lambert said there were human mummies in the Andes and some very good samples in Siberia, so the team was hopeful it would be able to measure the rate of human evolution.
They had already been studying the rate of evolution of Adelie penguins, which was possible because colonies of their ancestors' bones were frozen under the ice.
The penguins' rate of evolution was slightly lower than that of the tuatara.
Professor Lambert said such information was useful for evolutionary biologists when drawing the "tree of life", as it was important to be able to time the forks of the tree.
