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

  • Author / Creator
    Hammad, Ann O
  • 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.

  • Subjects / Keywords
  • Graduation date
    Fall 2015
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Specialization
    • Microbiology and Biotechnology
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Froese, Duane (Earth and Atmospheric Sciences)
    • Raivio, Tracy (Biological Sciences)
    • Boucher, Yan (Biological Sciences)