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Open Access Highly Accessed Research article

The impact of natural transformation on adaptation in spatially structured bacterial populations

Danesh Moradigaravand1* and Jan Engelstädter2

Author Affiliations

1 Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092 Zürich, Switzerland

2 School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia

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BMC Evolutionary Biology 2014, 14:141  doi:10.1186/1471-2148-14-141

Published: 20 June 2014

Abstract

Background

Recent studies have demonstrated that natural transformation and the formation of highly structured populations in bacteria are interconnected. In spite of growing evidence about this connection, little is known about the dynamics of natural transformation in spatially structured bacterial populations.

Results

In this work, we model the interdependency between the dynamics of the bacterial gene pool and those of environmental DNA in space to dissect the effect of transformation on adaptation. Our model reveals that even with only a single locus under consideration, transformation with a free DNA fragment pool results in complex adaptation dynamics that do not emerge in previous models focusing only on the gene shuffling effect of transformation at multiple loci. We demonstrate how spatial restriction on population growth and DNA diffusion in the environment affect the impact of transformation on adaptation. We found that in structured bacterial populations intermediate DNA diffusion rates predominantly cause transformation to impede adaptation by spreading deleterious alleles in the population.

Conclusion

Overall, our model highlights distinctive evolutionary consequences of bacterial transformation in spatially restricted compared to planktonic bacterial populations.

Keywords:
Bacterial adaptation; Bacterial transformation; Biofilm; Spatially structured populations