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Robert Karl Stonjek
Posted: Fri Mar 21, 2008 7:19 pm
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Tuatara, the fastest evolving animal

In a study of New Zealand's "living dinosaur" the tuatara, evolutionary
biologist, and ancient DNA expert, Professor David Lambert and his team from
the Allan Wilson Centre for Molecular Ecology and Evolution recovered DNA
sequences from the bones of ancient tuatara, which are up to 8000 years old.

They found that, although tuatara have remained largely physically unchanged
over very long periods of evolution, they are evolving - at a DNA level -
faster than any other animal yet examined. The research will be published in
the March issue of Trends in Genetics.

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

The rate of evolution for Adélie penguins, which Professor Lambert and his
team have studied in the Antarctic for many years, is slightly slower than
that of the tuatara. The tuatara rate is significantly faster than for
animals including the cave bear, lion, ox and horse.

"Of course we would have expected that the tuatara, which does everything
slowly - they grow slowly, reproduce slowly and have a very slow
metabolism - would have evolved slowly. In fact, at the DNA level, they
evolve extremely quickly, which supports a hypothesis proposed by the
evolutionary biologist Allan Wilson, who suggested that the rate of
molecular evolution was uncoupled from the rate of morphological evolution."

Allan Wilson was a pioneer of molecular evolution. His ideas were
controversial when introduced 40 years ago, but this new research supports
them.

Professor Lambert says the finding will be helpful in terms of future study
and conservation of the tuatara, and the team now hopes to extend the work
to look at the evolution of other animal species.

"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. There are human mummies in the Andes
and some very good samples in Siberia where we have some collaborators, so
we are hopeful we will be able to measure the rate of human evolution in
these animals too."

The tuatara, Sphendon punctatus, is found only in New Zealand and is the
only surviving member of a distinct reptilian order Sphehodontia that lived
alongside early dinosaurs and separated from other reptiles 200 million
years ago in the Upper Triassic period.

Source: Cell Press
http://www.physorg.com/news125234934.html

Posted by
Robert Karl Stonjek
 
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