Our results show that experimental evolution mimics evolution in nature. In particular, only 1000 generations of periodic recombination with immigrant genotypes is enough for linkage disequilibrium values in experimental populations to change from a maximum linkage value to a value similar to the one observed in wild strains of E. coli. Our analysis suggests an analogy between the recombination experiment and the evolutionary history of E. coli; the E. coli genome is a patchwork of genes laterally inserted in a common backbone, and the experimental E. coli chromosome is a patchwork where some sites are highly prone to recombination and others are very clonal. In addition, we propose a population model for wild E. coli where gene flow (recombination and migration) are an important source of genetic variation, and where certain hosts act as selective sieves; i.e., the host digestive system allows only certain strains to adhere and prosper as resident strains generating a particular microbiota in each host. Therefore we suggest that the strains from a wide range of wild hosts from different regions of the world may present an ecotypic structure where adaptation to the host may play an important role in the population structure.
|Original language||English (US)|
|Number of pages||11|
|Journal||Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology|
|State||Published - 2002|
Bibliographical noteFunding Information:
We wish to thank the numerous colleagues who assisted us in obtaining samples: D. Gordon collected all the Australian samples. B. Hernández, J. Golu-vov, M. Mandrujano, R. Medellin, S. Aguilar, O. Gaona, A. Mendoza, G. Pérez, L. Medrano, A. Nav-arro, J. Castillo, A. Zavala, B. Morales, R. Frías, A. Velázques, H. Arita, C. Alvarez, J. Charles, H. Charles, A. Miranda, D. Valenzuela, L. Sandner, R. Cerritos J. Ortega and several others collected the Mexican samples. We also thank Antonio Cruz, Laura Espinoza and Aldo Valera for valuable technical assistance. We are especially grateful to Richard Lenski who not only made this work possible by teaching us experimental evolution but also by showing us how to be critical with our work. This work was supported by DGAPA IN 218698 and CONACyT 27557 to VS, and CONACyT 27983-N to LEE.
- Escherichia coli
- Experimental evolution
- Genetic structure
- Population genetics
- Wild isolates