Bacteria are notorious for horizontal gene transfer, and it has often been asserted that this process will blur the boundaries between species to the extent that species cannot be clearly defined. Our study provides strong evidence that this is not necessarily so. Using 196 newly sequenced genomes of the Rhizobium leguminosarum species complex, we find five clearly distinct genospecies that occur in sympatry but show little evidence of recent between-species gene transfer affecting either the core or the accessory genome, except for a few highly mobile genetic regions.
Recommended citation: Cavassim, et al. (2020). “Symbiosis genes show a unique pattern of introgression and selection within a Rhizobium leguminosarum species complex.” Microbial Genomics. 1(1).