Chapter 20: Evolution and Medicine
Learning Objectives
20.1 Fever
20.1.a. Explain how “behavioral fever” in certain ectothermic vertebrates suggests that
fever is advantageous in dealing with infection.
20.1.b. Describe the proximate mechanisms responsible for fever in mammals.
20.1.c. Give evidence that supports the hypothesis that fever is an adaptation, including
fitness costs and benefits.
20.1.d. Apply the principle of asymmetric harm to both smoke detectors and fevers.
20.2 Vulnerability to Disease
20.2.a. Describe how Tinbergen’s four levels of explanation can be applied to illness,
disease, and medicine.
20.2.b. List Nesse and Williams’ six classes of evolutionary explanation for vulnerability
to disease.
20.3 Coevolutionary Arms Races between Pathogens and Hosts
20.3.a. Identify the advantages that pathogens have in the coevolutionary arms race with
their hosts.
20.3.b. Describe three ways that host immune systems can limit the ability of a pathogen
population to outrun the host despite the pathogen’s rapid evolution.
20.3.c. Explain the role of clonal selection in the vertebrate adaptive immune system,
including how V(D)J recombination generates a diverse repertoire of antibodies.
20.3.d. Give examples of ways that pathogens can subvert the host immune system.
20.3.e. Explain how host immune systems affect the phylogenetic pattern of pathogen
evolution, including the role of viral escape variants in reinfection.
20.4 The Evolution of Virulence
20.4.a. Define “virulence” and name one metric for quantifying the virulence of a
pathogen.
20.4.b. Discuss how virulence of the myxoma virus changed following its initial
introduction into Australian rabbit populations in the 1950s and explain how this scenario
exemplifies early views on the evolution of virulence.
20.4.c. List three possible reasons for why host mortality can change after the
introduction of a novel pathogen into a wild population.
20.4.d. Distinguish between the trade-off and short-sighted evolution models of virulence
evolution.
