These are two different but interrelated questions voiced by J.B.S. Haldane and Ronald Fisher in the 1930's. They are at the core of the unsolved problem of how complex adaptations evolve.
Dominance is an example of a genetic phenomenon.
We will take the example of dominance in biochemically determined traits to examine how these questions can be teased out in their physiological and evolutionary context. In the process we will address how dominance manifests itself in biochemical psystems and whether it can evolve.