In bacteria, the problem of DNA damage is most pronounced during periods of stress, particularly oxidative stress, that occur during crowding or starvation conditions. Under such conditions there is often only a single chromosome present. The finding that some bacteria induce competence under such stress conditions, supports the third hypothesis, that transformation exists to permit DNA repair. In experimental tests, bacterial cells exposed to agents damaging their DNA, and then undergoing transformation, survived better than cells exposed to DNA damage that did not undergo transformation (Hoelzer and Michod, 1991). In addition, competence to undergo transformation is often inducible by known DNA damaging agents (reviewed by Michod "et al"., 2008 and Bernstein "et al"., 2012). Thus, a strong short-term selective advantage for natural competence and transformation would be its ability to promote homologous recombinational DNA repair under conditions of stress. Such stress conditions might be incurred during bacterial infection of a susceptible host. Consistent with this idea, Li et al. reported that, among different highly transformable "S. pneumoniae" isolates, nasal colonization fitness and virulence (lung infectivity) depends on an intact competence system.