Which statement describes the neutral theory of molecular evolution?

Which statement describes the neutral theory of molecular evolution?

• A. Many mutations are beneficial and drive adaptation.
• B. Evolution is solely due to natural selection acting on advantageous mutations.
• C. Genetic drift does not influence evolution at the molecular level.
• D. Many mutations are selectively neutral; evolution at the molecular level is largely due to genetic drift.

Answer: (D)

The main idea is that most molecular changes are neutral and accumulate through random genetic drift rather than through natural selection. The neutral theory, introduced by Kimura, argues that many mutations do not affect an organism’s fitness, so their frequencies change mainly by chance from generation to generation. Over long timescales, these neutral substitutions accumulate, producing the patterns we see in molecular evolution. Selection still acts on mutations that alter phenotype and fitness, but such mutations are comparatively rare at the molecular level. The statement is consistent with that view: many mutations are selectively neutral, and evolution at the molecular level is largely due to genetic drift.

The main idea is that most molecular changes are neutral and accumulate through random genetic drift rather than through natural selection. The neutral theory, introduced by Kimura, argues that many mutations do not affect an organism’s fitness, so their frequencies change mainly by chance from generation to generation. Over long timescales, these neutral substitutions accumulate, producing the patterns we see in molecular evolution. Selection still acts on mutations that alter phenotype and fitness, but such mutations are comparatively rare at the molecular level. The statement is consistent with that view: many mutations are selectively neutral, and evolution at the molecular level is largely due to genetic drift.