26 July
2004
-OZONE
LOSS CAUSED GENETIC MUTATIONS AT TIME OF MASS EXTINCTION
Research
into the world’s worst mass extinction, which led to the loss of 90 per cent
of living species 250 million years ago, has found that the historical tragedy
also involved some disturbing genetics mutations.
Dr
Mark Sephton
The
Open University’s Dr Mark Sephton, who was part of an international team of
scientists from the Netherlands and the United Kingdom who uncovered the
remarkable new information, said: “The mother of all mass extinction just got
worse”.
The
findings are to appear in the latest Proceedings of the National Academy of
Sciences (PNAS) magazine, published today.
“In
our work we have found that at the time of the end-Permian extinction increased
amounts of ultraviolet light filtered through the Earth’s surface and caused
damage to the DNA in plant spores. The results were abnormalities that prevented
plant life from reproducing and a consequent collapse of terrestrial
ecosystems,” says
Dr Sephton.
“The
cause of the increased intensity of ultraviolet light was a disruption in the
Earth’s ozone shield. Massive volcanic activity that was taking place in
Siberia at this time forced chlorine and bromine containing gases into the
stratosphere where they catalytically destroyed ultraviolet-absorbing ozone
gases. It was only when volcanic activity subsided, that life on earth could
begin to recover from its biggest ever catastrophe,” he concluded.
Dr
Sephton believes the results heed an important warning for today’s society:
“We are bringing the effect of human activity on ozone depletion under control
but the end-Permian example shows us that natural volcanic activity can cancel
out all our good efforts”.
Editor’s
Note
The
article "Environmental Mutagenesis during the End-Permian Ecological
Crisis" which Dr Sephton co-wrote with Henk Visscher of Utrecht University
in the Netherlands will be published on PNAS’s Online Early Edition this week.
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