[Campbell Biology P.598] The 'WHAT IF?' scenario describes a highly lethal myxoma virus in E... | Practice Question

The 'WHAT IF?' scenario describes a highly lethal myxoma virus in European rabbits. If this virus is introduced to a rabbit population with no prior exposure, what long-term evolutionary trends are most likely to occur in the rabbit population and/or the virus?

  • A: The virus will become more lethal over time, leading to the complete extinction of the rabbit population.
  • B: Rabbits with natural resistance will be selected for, and the virus may evolve to be less virulent.
  • C: The rabbit population will develop behavioral resistance, learning to avoid mosquitoes.
  • D: The virus will rapidly mutate into a non-infectious form due to host mortality.

Explanation

This scenario describes co-evolution. A highly lethal pathogen that kills its hosts quickly limits its own transmission. Therefore, there's selective pressure for the virus to become less virulent allowing hosts to live longer and spread the virus more . Simultaneously, rabbits with any natural resistance to the virus will survive and reproduce, increasing the frequency of resistant genes in the population over generations. This leads to a co-evolutionary arms race where both species adapt.