Migration promotes plasmid stability under spatially heterogeneous positive selection

Bacteria–plasmid associations can be mutualistic or antagonistic depending on the strength of positive selection for plasmid-encoded genes, with contrasting outcomes for plasmid stability. In mutualistic environments, plasmids are swept to high frequency by positive selection, increasing the likelih...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2018-05, Vol.285 (1879), p.20180324-20180324
Main Authors: Harrison, Ellie, Hall, James P. J., Brockhurst, Michael A.
Format: Article
Language:English
Subjects:
Amelioration
Biological evolution
Coding
Compensatory Evolution
Ecology
Evolution
Extinction
Genes
Genetic recombination
Mercury
Migration
Mobile Genetic Element
Mutation
Negative selection
Plasmids
Positive selection
Pseudomonas fluorescens
Source-Sink
Spatial Heterogeneity
Species extinction
Species Interactions
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Summary:Bacteria–plasmid associations can be mutualistic or antagonistic depending on the strength of positive selection for plasmid-encoded genes, with contrasting outcomes for plasmid stability. In mutualistic environments, plasmids are swept to high frequency by positive selection, increasing the likelihood of compensatory evolution to ameliorate the plasmid cost, which promotes long-term stability. In antagonistic environments, plasmids are purged by negative selection, reducing the probability of compensatory evolution and driving their extinction. Here we show, using experimental evolution of Pseudomonas fluorescens and the mercury-resistance plasmid, pQBR103, that migration promotes plasmid stability in spatially heterogeneous selection environments. Specifically, migration from mutualistic environments, by increasing both the frequency of the plasmid and the supply of compensatory mutations, stabilized plasmids in antagonistic environments where, without migration, they approached extinction. These data suggest that spatially heterogeneous positive selection, which is common in natural environments, coupled with migration helps to explain the stability of plasmids and the ecologically important genes that they encode.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.2018.0324