[Campbell Biology P.569] Consider two species that diverged geographically but then resumed ... | Practice Question

Consider two species that diverged geographically but then resumed contact before complete reproductive isolation. Based on the principles discussed, what is the most likely long-term outcome if hybrid offspring consistently survive and reproduce more poorly than offspring from intraspecific matings, and there is no continued significant gene flow from outside the hybrid zone?

  • A: The two species will eventually fuse into a single species due to extensive interbreeding.
  • B: Reproductive barriers between the two species will likely be reinforced, leading to complete reproductive isolation.
  • C: A stable hybrid zone will form, with hybrids consistently outcompeting parent species in specific niches.
  • D: The hybrid offspring will develop novel adaptations, leading to the formation of a third, distinct species.

Explanation

When hybrid offspring are less fit than parent species offspring, natural selection will favor individuals that avoid interbreeding. This process, known as reinforcement, leads to the strengthening of reproductive barriers and ultimately to complete reproductive isolation between the two species.