1. Do you believe that evolution is progressive? Why or why not? What does the Great Chain of Being (or Scala Naturae) have to do with the notion of progress and goals in evolution? What view does current thinking in evolutionary biology overwhelmingly support?

2. Streptococcus pneumoniae, or pneumococcus, is a leading cause of respiratory illness (namely pneumonia) in children and the elderly. Intense antibiotic therapy for pneumococcal infections over the last few decades has resulted in the emergence of multi-drug resistant strains. For example, the graph below illustrates changes in resistance to penicillin by pneumococcus bacteria in Icelandic children. The use of penicillin was strongly discouraged starting in the early 1990’s with the results illustrated. (Data from Kristinsson, K. G. 1995. Epidemiology of penicillin resistant pneumococci in Iceland. Microbial Drug Resistance 1(2):121-125.)

Question:

Briefly describe the rationale underlying the general hypothesis that the use of antibiotics selects for resistance in bacteria. According to your understanding of coevolution in pathogens and hosts, is the trend toward decreased resistance following reduced use of antibiotics likely to continue? Explain why or why not. Lastly, how would you judge if host-pathogen dynamics such as this one arose due to coevolution?

250 words per question and 1 reference per question