 Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation, transformation and transduction, even between widely divergent species.This horizontal gene transfer, coupled with a high mutation rate and other means of transformation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses.This rapid evolution is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria, "superbugs", that are resistant to antibiotics.