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Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects

The most consistent result in more than two decades of experimental evolution is that the fitness of populations adapting to a constant environment does not increase indefinitely, but reaches a plateau. Using experimental evolution with bacteriophage, we show here that the converse is also true. In...

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Detalles Bibliográficos
Autores principales: Silander, Olin K, Tenaillon, Olivier, Chao, Lin
Formato: Texto
Lenguaje:English
Publicado: Public Library of Science 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1845161/
https://www.ncbi.nlm.nih.gov/pubmed/17407380
http://dx.doi.org/10.1371/journal.pbio.0050094
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author Silander, Olin K
Tenaillon, Olivier
Chao, Lin
author_facet Silander, Olin K
Tenaillon, Olivier
Chao, Lin
author_sort Silander, Olin K
collection PubMed
description The most consistent result in more than two decades of experimental evolution is that the fitness of populations adapting to a constant environment does not increase indefinitely, but reaches a plateau. Using experimental evolution with bacteriophage, we show here that the converse is also true. In populations small enough such that drift overwhelms selection and causes fitness to decrease, fitness declines down to a plateau. We demonstrate theoretically that both of these phenomena must be due either to changes in the ratio of beneficial to deleterious mutations, the size of mutational effects, or both. We use mutation accumulation experiments and molecular data from experimental evolution to show that the most significant change in mutational effects is a drastic increase in the rate of beneficial mutation as fitness decreases. In contrast, the size of mutational effects changes little even as organismal fitness changes over several orders of magnitude. These findings have significant implications for the dynamics of adaptation.
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spelling pubmed-18451612007-05-01 Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects Silander, Olin K Tenaillon, Olivier Chao, Lin PLoS Biol Research Article The most consistent result in more than two decades of experimental evolution is that the fitness of populations adapting to a constant environment does not increase indefinitely, but reaches a plateau. Using experimental evolution with bacteriophage, we show here that the converse is also true. In populations small enough such that drift overwhelms selection and causes fitness to decrease, fitness declines down to a plateau. We demonstrate theoretically that both of these phenomena must be due either to changes in the ratio of beneficial to deleterious mutations, the size of mutational effects, or both. We use mutation accumulation experiments and molecular data from experimental evolution to show that the most significant change in mutational effects is a drastic increase in the rate of beneficial mutation as fitness decreases. In contrast, the size of mutational effects changes little even as organismal fitness changes over several orders of magnitude. These findings have significant implications for the dynamics of adaptation. Public Library of Science 2007-04 2007-04-03 /pmc/articles/PMC1845161/ /pubmed/17407380 http://dx.doi.org/10.1371/journal.pbio.0050094 Text en © 2007 Silander et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Silander, Olin K
Tenaillon, Olivier
Chao, Lin
Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects
title Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects
title_full Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects
title_fullStr Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects
title_full_unstemmed Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects
title_short Understanding the Evolutionary Fate of Finite Populations: The Dynamics of Mutational Effects
title_sort understanding the evolutionary fate of finite populations: the dynamics of mutational effects
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1845161/
https://www.ncbi.nlm.nih.gov/pubmed/17407380
http://dx.doi.org/10.1371/journal.pbio.0050094
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