According to Natural Selection, it affects the physical because of the current environmental hazards affecting the biology of the organism in that environment. Correct? It serves to evolve those that are at a physical advantage, and cause those that are at a physical inconvenience to die before procreation among its own kind (and that's another point that I'll get to). Correct? So in this process, the physical adept evolve not to form new appendages or to learn new information but to survive in their current state (as it is exhibited in the insect scenario in the OP). Hypothetically, if a fish wanted to go on land, it would have to gradually develop the ability to do so over many generations. Correct? Answer: Limbs. ...but what does this do to the biology of the animal? Answer: It becomes no longer streamlined; and so, according to Natural Selection, it naturally dies, but that species is preserved from mutations and extra-genetics. No matter how evolution causes biology to evolve. It isn't by the dogma of Natural Selection since it contradicts the process of evolution.