Chapter 16.2, Problem 1CSC

Evolution of a Menace

The mutant alleles that confer antibiotic resistance on members of a bacterial population can move to other populations by gene flow and increase by genetic drift. For example. MRSA living on a person's skin might be transferred to her roommate's skin via a shared towel or article of clothing. After joining the population of nonresistant bacteria on the roommate's skin, the newly arrived MRSA may reproduce and may even transfer resistance alleles directly to local bacteria through a process known as conjugation (see Chapter 20). The resistance alleles, introduced to the bacterial population on the roommate's skin by gene flow, may subsequently experience genetic drift that increases their frequency. But what will happen if antibiotics are introduced to the new environment (that is. the roommate's body)? Find out in Section 16.3.