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Front. Microbiol. | doi: 10.3389/fmicb.2019.00245

Historical factors associated with past environments influence the biogeography of thermophilic endospores in Arctic marine sediments

  • 1Queen Mary University of London, United Kingdom
  • 2Newcastle University, United Kingdom
  • 3Stanford University, United States
  • 4University of Vienna, Austria
  • 5Austrian Polar Research Institute, Austria
  • 6Max Planck Institute for Marine Microbiology (MPG), Germany
  • 7Aarhus University, Denmark
  • 8University of Calgary, Canada

Selection by the local, contemporary environment plays a prominent role in shaping the biogeography of microbes. However, the importance of historical factors in microbial biogeography is more debatable. Historical factors include past ecological and evolutionary circumstances that may have influenced present-day microbial diversity, such as dispersal and past environmental conditions. Diverse thermophilic sulphate-reducing Desulfotomaculum are present as dormant endospores in marine sediments worldwide where temperatures are too low to support their growth. Therefore, they are dispersed to here from elsewhere, presumably a hot, anoxic habitat. While dispersal through ocean currents must influence their distribution in cold marine sediments, it is not clear whether even earlier historical factors, related to the source habitat where these organisms were once active, also have an effect. We investigated whether these historical factors may have influenced the diversity and distribution of thermophilic endospores by comparing their diversity in 10 Arctic fjord surface sediments. Although community composition varied spatially, clear biogeographic patterns were only evident at a high level of taxonomic resolution (>97% sequence similarity of the 16S rRNA gene) achieved with oligotyping. In particular, the diversity and distribution of oligotypes differed for the two most prominent OTUs (defined using a standard 97% similarity cutoff). One OTU was dominated by a single ubiquitous oligotype, while the other OTU consisted of ten more spatially localised oligotypes that decreased in compositional similarity with geographic distance. These patterns are consistent with differences in historical factors that occurred when and where the taxa were once active, prior to sporulation. Further, the influence of history on biogeographic patterns was only revealed by analysing microdiversity within OTUs, suggesting that populations within standard OTU-level groupings do not necessarily share a common ecological and evolutionary history.

Keywords: biogeography, thermophile, Endospore, marine sediment, Desulfotomaculum, sulphate-reducing bacteria, Dispersal

Received: 04 Sep 2018; Accepted: 29 Jan 2019.

Edited by:

Martin Koenneke, Center for Marine Environmental Sciences, University of Bremen, Germany

Reviewed by:

Jesse G. Dillon, California State University, Long Beach, United States
Jiasong Fang, Hawaii Pacific University, United States
Henrik Sass, Cardiff University, United Kingdom  

Copyright: © 2019 Hanson, Mueller, Loy, Dona, Appel, Jørgensen and Hubert. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. China A. Hanson, Queen Mary University of London, London, United Kingdom, c.hanson@qmul.ac.uk