Dear Doug;-
You wrote: "Mutations generally do not improve species."
True, true! It is the term "generally" that allows for speciation.
Species may be improved by only one out of 100, one out of 1000
mutations. But the magnitude of time allows for that. The 99 or 999
didn't make it. But, as Oliver Wendell Holmes once said about quite a
different matter: "Thank God for the one!"
Art