To add to the stash of dangerously simplifying computer analogies, this almost sounds like separate "code" and "data" sections: The coding DNA sort of interpret

To add to the stash of dangerously simplifying computer analogies, this almost sounds like separate "code" and "data" sections: The coding DNA sort of interpreting the non-coding part as "data". The advantage is the same: The coding parts can evolve only slowly, because a wrong mutation can mess up the entire functioning of the wings and would seriously reduce the individual's chance of survival. Meanwhile, a mutation in the non-coding part can only change the color pattern and nothing else. Therefore, the non-coding part can evolve a lot faster.