Distinguishing the effects of mutational biases and natural selection on DNA sequence variation

A clarification of the distinction between mutational and natural selection biases is attempted while proposing some techniques of differentiating between changes in mutation patterns and natural selection actions. The mutation configurations of DNA sequences will not differ if four assumptions are met. However, Adam Eyre-Walker's assumption has differed from the third assumption. Comparing base composition evolution and mutation evolutionary dynamics are two methods to distinguish between selection and mutation biases when interpreting departures from the four assumptions.