Environmental mutagenesis during the end-Permian ecological crisis.
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.
Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands. h.visscher@bio.uu.nl
Henk
H
Visscher
Cindy V
CV
Looy
Margaret E
ME
Collinson
Henk
H
Brinkhuis
Johanna H A
JH
van Konijnenburg-van Cittert
Wolfram M
WM
Kürschner
Mark A
MA
Sephton
D004247:DNA / Q000235:genetics*; D019143:Evolution, Molecular; D009154:Mutation; D019021:Natural History; D010126:Ozone; D010944:Plants / Q000235:genetics; D011058:Pollen / Q000235:genetics; D013170:Spores / Q000235:genetics; D014466:Ultraviolet Rays
D010126:Ozone; D004247:DNA