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Microbial community dynamics from permafrost across the Pleistocene-Holocene boundary and response to abrupt climate change Open Access


Other title
Pleistocene-Holocene boundary
microbial community changes
Type of item
Degree grantor
University of Alberta
Author or creator
Hammad, Ann O
Supervisor and department
Lanoil, Brian (Biological Sciences)
Examining committee member and department
Raivio, Tracy (Biological Sciences)
Boucher, Yan (Biological Sciences)
Froese, Duane (Earth and Atmospheric Sciences)
Department of Biological Sciences
Microbiology and Biotechnology
Date accepted
Graduation date
Master of Science
Degree level
Permafrost houses active microbial communities adapted to constant sub-zero temperatures and anaerobic conditions. These extreme conditions make permafrost an excellent archive for long-term DNA preservation. Recent studies in the laboratory have shown a shift in permafrost bacterial communities upon thaw while experimental warming of Arctic soils in field experiments, some exceeding a decade, have failed to show significant changes. This discrepancy may reflect that previous studies may have been biased because DNA from non-viable cells is well preserved in permafrost and may be PCR amplified. Here we distinguish between DNA originating from viable cells and total bacterial DNA extracted from permafrost. We examine the response of the active bacterial community composition to the rapid warming that accompanied the end of the Pleistocene, 11,700 years ago. This warming resulted in changes in soil edaphic properties, including pH, TOC and TN as a largely grassland ecosystem was replaced by early boreal forest. Our results show that the viable permafrost bacterial community is significantly different from total DNA and these two assemblages are structured by different environmental parameters. The corollary to these findings is that future climate change is unlikely to shift bacterial communities unless the warming is sufficient to change soil edaphic properties.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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