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The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa

BACKGROUND: A common form of cooperation in bacteria is based on the secretion of beneficial metabolites, shareable as public good among cells within a group. Because cooperation can be exploited by “cheating” mutants, which contribute less or nothing to the public good, there has been great interes...

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Autores principales: Granato, Elisa T., Kümmerli, Rolf
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5594463/
https://www.ncbi.nlm.nih.gov/pubmed/28893176
http://dx.doi.org/10.1186/s12862-017-1060-6
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author Granato, Elisa T.
Kümmerli, Rolf
author_facet Granato, Elisa T.
Kümmerli, Rolf
author_sort Granato, Elisa T.
collection PubMed
description BACKGROUND: A common form of cooperation in bacteria is based on the secretion of beneficial metabolites, shareable as public good among cells within a group. Because cooperation can be exploited by “cheating” mutants, which contribute less or nothing to the public good, there has been great interest in understanding the conditions required for cooperation to remain evolutionarily stable. In contrast, much less is known about whether cheats, once fixed in the population, are able to revert back to cooperation when conditions change. Here, we tackle this question by subjecting experimentally evolved cheats of Pseudomonas aeruginosa, partly deficient for the production of the iron-scavenging public good pyoverdine, to conditions previously shown to favor cooperation. RESULTS: Following approximately 200 generations of experimental evolution, we screened 720 evolved clones for changes in their pyoverdine production levels. We found no evidence for the re-evolution of full cooperation, even in environments with increased spatial structure, and reduced costs of public good production – two conditions that have previously been shown to maintain cooperation. In contrast, we observed selection for complete abolishment of pyoverdine production. The patterns of complete trait degradation were likely driven by “cheating on cheats” in unstructured, iron-limited environments where pyoverdine is important for growth, and selection against a maladaptive trait in iron-rich environments where pyoverdine is superfluous. CONCLUSIONS: Our study shows that the path to re-evolve public-goods cooperation can be constrained. While a limitation of the number of mutational targets potentially leading to reversion might be one reason for the observed pattern, an alternative explanation is that the selective conditions required for revertants to spread from rarity are much more stringent than those needed to maintain cooperation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12862-017-1060-6) contains supplementary material, which is available to authorized users.
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spelling pubmed-55944632017-09-14 The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa Granato, Elisa T. Kümmerli, Rolf BMC Evol Biol Research Article BACKGROUND: A common form of cooperation in bacteria is based on the secretion of beneficial metabolites, shareable as public good among cells within a group. Because cooperation can be exploited by “cheating” mutants, which contribute less or nothing to the public good, there has been great interest in understanding the conditions required for cooperation to remain evolutionarily stable. In contrast, much less is known about whether cheats, once fixed in the population, are able to revert back to cooperation when conditions change. Here, we tackle this question by subjecting experimentally evolved cheats of Pseudomonas aeruginosa, partly deficient for the production of the iron-scavenging public good pyoverdine, to conditions previously shown to favor cooperation. RESULTS: Following approximately 200 generations of experimental evolution, we screened 720 evolved clones for changes in their pyoverdine production levels. We found no evidence for the re-evolution of full cooperation, even in environments with increased spatial structure, and reduced costs of public good production – two conditions that have previously been shown to maintain cooperation. In contrast, we observed selection for complete abolishment of pyoverdine production. The patterns of complete trait degradation were likely driven by “cheating on cheats” in unstructured, iron-limited environments where pyoverdine is important for growth, and selection against a maladaptive trait in iron-rich environments where pyoverdine is superfluous. CONCLUSIONS: Our study shows that the path to re-evolve public-goods cooperation can be constrained. While a limitation of the number of mutational targets potentially leading to reversion might be one reason for the observed pattern, an alternative explanation is that the selective conditions required for revertants to spread from rarity are much more stringent than those needed to maintain cooperation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12862-017-1060-6) contains supplementary material, which is available to authorized users. BioMed Central 2017-09-11 /pmc/articles/PMC5594463/ /pubmed/28893176 http://dx.doi.org/10.1186/s12862-017-1060-6 Text en © The Author(s). 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Granato, Elisa T.
Kümmerli, Rolf
The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa
title The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa
title_full The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa
title_fullStr The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa
title_full_unstemmed The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa
title_short The path to re-evolve cooperation is constrained in Pseudomonas aeruginosa
title_sort path to re-evolve cooperation is constrained in pseudomonas aeruginosa
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5594463/
https://www.ncbi.nlm.nih.gov/pubmed/28893176
http://dx.doi.org/10.1186/s12862-017-1060-6
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