Models of compensatory molecular evolution: effects of back mutation.

Compensatory mutations are individually deleterious but appropriate combinations of mutants are harmless. For several models of compensatory molecular evolution, we consider the effects of back mutation. It is shown that the effects of back mutation on the rate of compensatory molecular evolution are weak. Further we estimate the values of selection parameter of deleterious single mutants for the models of compensatory molecular evolution both with and without back mutation using sequence data of folded RNA molecules and compare them with the previous results.