Ecology of the rare microbial biosphere of the Arctic Ocean

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Galand, Pierre E., Casamayor, Emilio O., Kirchman, David L., Lovejoy, Connie
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Academy of Sciences (U.S.) 2009
• Subjects: Abundance distribution; Bacteria; Archaea; Pyrosequencing; Biogeographya; Arctic; Arctic Ocean; Canada; ArcticNet; International Polar Year
• Online Access: http://hdl.handle.net/10261/21166; https://doi.org/10.1073/pnas.0908284106

Understanding the role of microbes in the oceans has focused on taxa that occur in high abundance; yet most of the marine microbial diversity is largely determined by a long tail of low-abundance taxa. This rare biosphere may have a cosmopolitan distribution because of high dispersal and low loss rates, and possibly represents a source of phylotypes that become abundant when environmental conditions change. However, the true ecological role of rare marine microorganisms is still not known. Here, we use pyrosequencing to describe the structure and composition of the rare biosphere and to test whether it represents cosmopolitan taxa or whether, similar to abundant phylotypes, the rare community has a biogeography. Our examination of 740,353 16S rRNA gene sequences from 32 bacterial and archaeal communities from various locations of the Arctic Ocean showed that rare phylotypes did not have a cosmopolitan distribution but, rather, followed patterns similar to those of the most abundant members of the community and of the entire community. The abundance distributions of rare and abundant phylotypes were different, following a log-series and log-normal model, respectively, and the taxonomic composition of the rare biosphere was similar to the composition of the abundant phylotypes. We conclude that the rare biosphere has a biogeography and that its tremendous diversity is most likely subjected to ecological processes such as selection, speciation, and extinction. This work was supported by Marie Curie Grant CRENARC MEIF-CT-2007–040247 (to P.E.G.); Spanish Grant CGL2006–12058-BOS (to E.O.C.); a grant from the Natural Sciences and Engineering Council, Canada, Special Research Opportunity Fund and ArcticNet (C.L.); National Science Foundation GrantOPP0632233(to D.K.);andaKeck foundation grant to the International Census of Marine Microbes led by M. Sogin and L. Ameral Zettler. Financial and ship time support were also provided by Fisheries and Oceans Canada and the International Polar Year Programs’ Canada’s Three ...