Rolling the evolutionary dice: commensals as proxies for elucidating the underpinnings of antibiotic resistance mechanisms and evolution in human pathogens.

Species within the genus are adept at sharing adaptive allelic variation, with commensal species repeatedly transferring resistance to their pathogenic relative . However, resistance in commensals is infrequently characterized, limiting our ability to predict novel and potentially transferable resistance mechanisms that ultimately may become important clinically. Unique evolutionary starting places of each species will have distinct genomic backgrounds, which may ultimately control the fate of evolving populations in response to selection as epistatic and additive interactions coerce lineages along divergent evolutionary trajectories.