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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