OK, last aside.... but I think that a substitution type mutation WOULD increase entropy on a species wide perspective since it would increase variation of the gene within the space under consideration.
It would not increase the entropy.
Entropy is an energy-related property. Variation is not.
The amount of entropy in a system has absolutely nothing to do with the variation in a particular species (i.e. the number of different base pairs at a particular locus).
It really does not require an expert understanding. It's as simple as the fact that one does not affect the other at all.