Evolutive ecology of Escherichia coli

Escherichia coli is the best known organism in terns of its genetics and ph ysiology. However, very little is understood about its ecology and evolutio nary biology: In this paper we review some aspects of its biology, genomics , ecology: and population genetics. Classic studies, mostly based on human strains, suggested that E. coli was a clonal bacteria showing little recomb ination. We hate built and analyzed a collection called IECOL, with over 20 00 bacterial strains front animals from several places in the world, humans from Mexico and wild strains,from different environments. In this studs; t he report population genetics and molecular evolution data from E. coli in this collection. These results, together with recently published studies, s hots that E. coli is a very diverse organism with a dynamic genome. Recombi nation is important and the successful combinations can spread in an epidem ic way within human and animal populations, giving a false signal of clonal ity. Finally the potential use of the IECOL collection is illustrated using examples of our studies about the evolution of mutation rates and pathogen ic genes.