Journal Article

Evolution without Species: The Case of Mosaic Bacteriophages

Gregory J. Morgan and W. Brad Pitts

in The British Journal for the Philosophy of Science

Published on behalf of British Society for the Philosophy of Science

Volume 59, issue 4, pages 745-765
Published in print December 2008 | ISSN: 0007-0882
Published online December 2008 | e-ISSN: 1464-3537 | DOI:
Evolution without Species: The Case of Mosaic Bacteriophages

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Recent work in viral genomics has shown that bacteriophages exhibit a high degree of mosaicism, which is most likely due to a long history of prolific horizontal gene transfer (HGT). Given these findings, we argue that each of the most plausible attempts to properly classify bacteriophages into distinct species fail. Mayr's biological species concept fails because there is no useful viral analog to sexual reproduction. Phenetic species concepts fail because they obscure the mosaicism and the rich reticulated viral histories. Phylogenetic species concepts, even when extended to take into account reticulation, fail because there is no non-arbitrary distinction between recombination events that create a new viral species and those that do not. There is good reason to think that bacteriophages, arguably the Earth's most abundant biological agent, evolve without forming species.


The Biology of Viruses


Bacteriophage life cycles


Mechanisms of HGT

The Species Problem and Species Concepts


Phenetic species concepts


The biological species concept


Phylogenetic species concepts


The ecological species concept


Homeostatic property cluster species

Viruses and Species Taxonomy

Reticular Phylogenies


Journal Article.  7594 words.  Illustrated.

Subjects: Philosophy of Science ; Science and Mathematics

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