Environmental mutagenesis during the end-Permian ecological crisis
- Henk Visscher*,†,
- Cindy V. Looy*,‡,
- Margaret E. Collinson§,
- Henk Brinkhuis*,
- Johanna H. A. van Konijnenburg-van Cittert*,¶,
- Wolfram M. Kürschner*, and
- Mark A. Sephton∥
- *Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands; ‡Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, 10th Street and Constitution Avenue NW, Washington, DC 20560-0121; §Geology Department, Royal Holloway University of London, Egham TW20 0EX, United Kingdom; ¶National Museum of Natural History “Naturalis,” P.O. Box 9517, 2300 RA Leiden, The Netherlands; and ∥Planetary and Space Sciences Research Institute, Open University, Milton Keynes MK7 6AA, United Kingdom
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Communicated by David L. Dilcher, University of Florida, Gainesville, FL, June 22, 2004 (received for review January 26, 2004)
Abstract
During the end-Permian ecological crisis, terrestrial ecosystems experienced preferential dieback of woody vegetation. Across the world, surviving herbaceous lycopsids played a pioneering role in repopulating deforested terrain. We document that the microspores of these lycopsids were regularly released in unseparated tetrads indicative of failure to complete the normal process of spore development. Although involvement of mutation has long been hinted at or proposed in theory, this finding provides concrete evidence for chronic environmental mutagenesis at the time of global ecological crisis. Prolonged exposure to enhanced UV radiation could account satisfactorily for a worldwide increase in land plant mutation. At the end of the Permian, a period of raised UV stress may have been the consequence of severe disruption of the stratospheric ozone balance by excessive emission of hydrothermal organohalogens in the vast area of Siberian Traps volcanism.
Footnotes
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↵ † To whom correspondence should be addressed. E-mail: h.visscher{at}bio.uu.nl.
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Abbreviation: P-Tr, Permian–Triassic.
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See Commentary on page 12779.
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↵ ** Foster, C. B., Oral Presentation, 15th International Congress on Carboniferous and Permian Stratigraphy, Aug. 10–16, 2003, Utrecht, The Netherlands.
- Copyright © 2004, The National Academy of Sciences
