dN/dS ratio < 1 suggests:
Purifying selection reflects key principle in quiz on molecular evolution pyqs solved -sec d, where evolutionary mechanisms shape genetic variation and adaptation. In this context, Purifying selection aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why Purifying selection fits helps integrate natural selection, environment.
Ref: Nei & Kumar, Molecular Evolution, Clocks and Purifying Selection.