What prevents micro evolution from becoming macro evolution

This isn't an accurate characterization of what evolutionary biologists say. Through natural selection, deleterious mutations are removed and advantageous mutations retained. It is advantageous mutations (and to be more complete, also mostly neutral mutations) that accumulate, not all mutations. Because your characterization of the position of evolutionary biologists was incomplete, this characterization of the position of creationists fails to address the fact that deleterious mutations are removed from populations by natural selection and are not included among the mutations that accumulate.--Percy

Hi WK,I made clear I was aware of the neutral and nearly neutral theories when I parenthetically said, "and to be more complete, also mostly neutral mutations." If you don't like the level of detail I've chosen then make your own arguments at your own chosen level of detail to Slevesque.--Percy

I wouldn't sweat it too much. When you said "transcription" instead of "replication," I think your meaning was pretty clear from context anyway.--Percy