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Biological Species Are Universal across Life’s Domains

Delineation of species is fundamental to organizing and understanding biological diversity. The most widely applied criterion for distinguishing species is the Biological Species Concept (BSC), which defines species as groups of interbreeding individuals that remain reproductively isolated from othe...

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Autores principales: Bobay, Louis-Marie, Ochman, Howard
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381558/
https://www.ncbi.nlm.nih.gov/pubmed/28186559
http://dx.doi.org/10.1093/gbe/evx026
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author Bobay, Louis-Marie
Ochman, Howard
author_facet Bobay, Louis-Marie
Ochman, Howard
author_sort Bobay, Louis-Marie
collection PubMed
description Delineation of species is fundamental to organizing and understanding biological diversity. The most widely applied criterion for distinguishing species is the Biological Species Concept (BSC), which defines species as groups of interbreeding individuals that remain reproductively isolated from other such groups. The BSC has broad appeal; however, many organisms, most notably asexual lineages, cannot be classified according to the BSC. Despite their exclusively asexual mode of reproduction, Bacteria and Archaea can transfer and exchange genes though homologous recombination. Here we show that barriers to homologous gene exchange define biological species in prokaryotes with the same efficacy as in sexual eukaryotes. By analyzing the impact of recombination on the polymorphisms in thousands of genome sequences, we find that over half of named bacterial species undergo continuous recombination among sequenced constituents, indicative of true biological species. However, nearly a quarter of named bacterial species show sharp discontinuities and comprise multiple biological species. These interruptions of gene flow are not a simple function of genome identity, indicating that bacterial speciation does not uniformly proceed by the gradual divergence of genome sequences. The same genomic approach based on recombinant polymorphisms retrieves known species boundaries in sexually reproducing eukaryotes. Thus, a single biological species definition based on gene flow, once thought to be limited only to sexually reproducing organisms, is applicable to all cellular lifeforms.
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spelling pubmed-53815582017-04-10 Biological Species Are Universal across Life’s Domains Bobay, Louis-Marie Ochman, Howard Genome Biol Evol Research Article Delineation of species is fundamental to organizing and understanding biological diversity. The most widely applied criterion for distinguishing species is the Biological Species Concept (BSC), which defines species as groups of interbreeding individuals that remain reproductively isolated from other such groups. The BSC has broad appeal; however, many organisms, most notably asexual lineages, cannot be classified according to the BSC. Despite their exclusively asexual mode of reproduction, Bacteria and Archaea can transfer and exchange genes though homologous recombination. Here we show that barriers to homologous gene exchange define biological species in prokaryotes with the same efficacy as in sexual eukaryotes. By analyzing the impact of recombination on the polymorphisms in thousands of genome sequences, we find that over half of named bacterial species undergo continuous recombination among sequenced constituents, indicative of true biological species. However, nearly a quarter of named bacterial species show sharp discontinuities and comprise multiple biological species. These interruptions of gene flow are not a simple function of genome identity, indicating that bacterial speciation does not uniformly proceed by the gradual divergence of genome sequences. The same genomic approach based on recombinant polymorphisms retrieves known species boundaries in sexually reproducing eukaryotes. Thus, a single biological species definition based on gene flow, once thought to be limited only to sexually reproducing organisms, is applicable to all cellular lifeforms. Oxford University Press 2017-03-01 /pmc/articles/PMC5381558/ /pubmed/28186559 http://dx.doi.org/10.1093/gbe/evx026 Text en © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. http://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Research Article
Bobay, Louis-Marie
Ochman, Howard
Biological Species Are Universal across Life’s Domains
title Biological Species Are Universal across Life’s Domains
title_full Biological Species Are Universal across Life’s Domains
title_fullStr Biological Species Are Universal across Life’s Domains
title_full_unstemmed Biological Species Are Universal across Life’s Domains
title_short Biological Species Are Universal across Life’s Domains
title_sort biological species are universal across life’s domains
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381558/
https://www.ncbi.nlm.nih.gov/pubmed/28186559
http://dx.doi.org/10.1093/gbe/evx026
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