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dc.contributor.authorStock, Alexandra  Concept link
dc.contributor.authorEdgcomb, Virginia P.  Concept link
dc.contributor.authorOrsi, William D.  Concept link
dc.contributor.authorFilker, Sabine  Concept link
dc.contributor.authorBreiner, Hans-Werner  Concept link
dc.contributor.authorYakimov, Michail M.  Concept link
dc.contributor.authorStoeck, Thorsten  Concept link
dc.identifier.citationBMC Microbiology 13 (2013): 150en_US
dc.description© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Microbiology 13 (2013): 150, doi:10.1186/1471-2180-13-150.en_US
dc.description.abstractDeep hypersaline anoxic basins (DHABs) are isolated habitats at the bottom of the eastern Mediterranean Sea, which originate from the ancient dissolution of Messinian evaporites. The different basins have recruited their original biota from the same source, but their geological evolution eventually constituted sharp environmental barriers, restricting genetic exchange between the individual basins. Therefore, DHABs are unique model systems to assess the effect of geological events and environmental conditions on the evolution and diversification of protistan plankton. Here, we examine evidence for isolated evolution of unicellular eukaryote protistan plankton communities driven by geological separation and environmental selection. We specifically focused on ciliated protists as a major component of protistan DHAB plankton by pyrosequencing the hypervariable V4 fragment of the small subunit ribosomal RNA. Geospatial distributions and responses of marine ciliates to differential hydrochemistries suggest strong physical and chemical barriers to dispersal that influence the evolution of this plankton group. Ciliate communities in the brines of four investigated DHABs are distinctively different from ciliate communities in the interfaces (haloclines) immediately above the brines. While the interface ciliate communities from different sites are relatively similar to each other, the brine ciliate communities are significantly different between sites. We found no distance-decay relationship, and canonical correspondence analyses identified oxygen and sodium as most important hydrochemical parameters explaining the partitioning of diversity between interface and brine ciliate communities. However, none of the analyzed hydrochemical parameters explained the significant differences between brine ciliate communities in different basins. Our data indicate a frequent genetic exchange in the deep-sea water above the brines. The “isolated island character” of the different brines, that resulted from geological events and contemporary environmental conditions, create selective pressures driving evolutionary processes, and with time, lead to speciation and shape protistan community composition. We conclude that community assembly in DHABs is a mixture of isolated evolution (as evidenced by small changes in V4 primary structure in some taxa) and species sorting (as indicated by the regional absence/presence of individual taxon groups on high levels in taxonomic hierarchy).en_US
dc.description.sponsorshipThis work was funded by NSF grants OCE-0849578 and OCE- 1061774 to VE and support from Carl Zeiss fellowship to AS and from the Deutsche Forschungsgemeinschaft (grants STO414/3-2 and STO414/7-1) to TS.en_US
dc.publisherBioMed Centralen_US
dc.rightsAttribution 2.0 Generic*
dc.subjectDeep-sea anoxic basinsen_US
dc.subjectSpecies sortingen_US
dc.subjectEnvironmental filteringen_US
dc.subjectNiche separationen_US
dc.titleEvidence for isolated evolution of deep-sea ciliate communities through geological separation and environmental selectionen_US

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