[Campbell Biology P.596] Based on the provided text, especially the discussion on sticklebac... | Practice Question

Based on the provided text, especially the discussion on stickleback fish and Concept Check 25.5, which statement best predicts the role of noncoding DNA in evolution?

  • A: Changes in noncoding DNA, particularly regulatory regions, are highly likely to be affected by natural selection because they can alter gene expression and thus phenotype, leading to morphological changes.
  • B: Noncoding DNA is 'junk DNA' and therefore immune to the forces of natural selection, as it has no functional impact.
  • C: Natural selection primarily acts on changes within protein-coding regions, while noncoding DNA changes are generally neutral.
  • D: Alterations in noncoding DNA always lead to detrimental effects, making them targets for purifying selection only.

Explanation

The stickleback fish example explicitly shows that changes in a noncoding regulatory region Pel enhancer of DNA can significantly alter gene expression and lead to substantial morphological changes reduction of spines . Since these morphological changes can affect fitness e.g., in environments without predators , they become targets for natural selection. Concept Check 25.5, question 3, further prompts the reader to predict that noncoding DNA is likely affected by natural selection given its role in morphological change.