[Campbell Biology P.600] The evolution of the tetrapod limb was significantly aided by a gen... | Practice Question

The evolution of the tetrapod limb was significantly aided by a genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud rather than farther back. This example best illustrates which evolutionary principle?

  • A: Paedomorphosis, where juvenile features are retained in the adult form.
  • B: Exaptation, where a structure evolves for one purpose but is co-opted for another.
  • C: A change in the regulation or expression of a developmental gene altering the spatial organization of body parts.
  • D: Genetic drift leading to random changes in limb morphology.

Explanation

The example clearly states that a change in the expression location of a Hox gene led to the evolution of the tetrapod limb by altering the spatial organization of body parts where the limb bud formed . This directly illustrates how changes in developmental genes or their regulation can drive evolutionary novelty.