Selective sweep is a process in which a new mutation that confers a selective advantage is dispersed throughout the population.
While widely investigated in eukaryotes, selective sweeps received little to no attention in microbial studies. It was commonly assumed that bacteria have low recombination rates and that once a bacterium gains an adaptive mutation, clonal expansion is more likely to happen than recombination. Thus, searching for sweeps among bacterial populations was considered to be fruitless.
However, in our previous study (Oren et al. PNAS 2014), which examined regulatory transfer across different bacterial clades, we detected several cases of promoters that underwent a clear selective sweep. These surprising observations suggest that selective sweeps in bacteria may be much more common than previously thought.
We are currently developing novel methodologies to detect selective sweep events in bacteria. Our approach accounts for bacterial-specific characteristics, such as the high sequence variability between strains. The methodologies are characterized on simulated data and are applied to detect sweeps among several bacterial species, for which enough strains were sequenced.
Detecting selective sweeps in bacteria would allow for a better understanding of the evolutionary mechanisms underlying bacterial infections. Such understanding may contribute to the ongoing effort to detect and fight pathogens.
