PERIODIC SELECTION, INFECTIOUS GENE EXCHANGE AND THE GENETIC STRUCTURE OF E. COLI POPULATIONS

摘要: As a consequence of sequential replacements by clones higher fitness (periodic selection), bacterial populations would be continually purged genetic variability, and the fate selectively neutral alleles in very large bacteria similar to that demes sexually reproducing organisms with small genetically effective population sizes. The significance periodic selection reducing variability these clonally species is dependent on amount exchange between (recombination). In an effort determine relationship rates selection, recombination sizes populations, model for infectious gene has been developed its properties analyzed. It shows that, given regime, size increases exponentially rate recombination.--With parameters this range anticipated natural E. coli, purging effects are significant; individual or lineages have sizes.--Based result, some other priori considerations review results epidemiological studies, it postulated coli composed relatively limited number geographically widespread nearly isolated monomorphic lineages. implications structure interpretation protein variation hypothesis discussed.