ANTIBIOTIC RESISTANCE AND STRESS IN THE LIGHT OF FISHER'S MODEL
Article first published online: 10 JUL 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 12, pages 3815–3824, December 2012
How to Cite
Trindade, S., Sousa, A. and Gordo, I. (2012), ANTIBIOTIC RESISTANCE AND STRESS IN THE LIGHT OF FISHER'S MODEL. Evolution, 66: 3815–3824. doi: 10.1111/j.1558-5646.2012.01722.x
- Issue published online: 3 DEC 2012
- Article first published online: 10 JUL 2012
- Accepted manuscript online: 25 JUN 2012 09:05AM EST
- Received March 1, 2012 Accepted June 4, 2012
- Distribution of fitness effects;
- fitness landscape;
The role of mutations in evolution depends upon the distribution of their effects on fitness. This distribution is likely to depend on the environment. Indeed genotype-by-environment interactions are key for the process of local adaptation and ecological specialization. An important trait in bacterial evolution is antibiotic resistance, which presents a clear case of change in the direction of selection between environments with and without antibiotics. Here, we study the distribution of fitness effects of mutations, conferring antibiotic resistance to Escherichia coli, in benign and stressful environments without drugs. We interpret the distributions in the light of a fitness landscape model that assumes a single fitness peak. We find that mutation effects (s) are well described by a shifted gamma distribution, with a shift parameter that reflects the distance to the fitness peak and varies across environments. Consistent with the theoretical predictions of Fisher's geometrical model, with a Gaussian relationship between phenotype and fitness, we find that the main effect of stress is to increase the variance in s. Our findings are in agreement with the results of a recent meta-analysis, which suggest that a simple fitness landscape model may capture the variation of mutation effects across species and environments.