As one article notes, micro-evolution + 3.8 billion years = macro-evolution.
Fossil records make it pretty clear that species appeared over an extended period of time. Of course, that's about when the creationists start telling us that the world is only a few thousand years old and that the fossil evidence is meaningless.
Evolution is seen routinely in viruses, but even there decades and even centuries are needed for the emergence of a new species. However, HIV-1 evolved from Simian Immunodeficiency Virus (SIV) over the last century. Most pandemics are attributed to the evolution of new virus species. That, of course, is when creationists throw in words such as "a higher atomically different species or substance" as Keith does in his comments. Viruses, they argue, are not a "higher" form and therefore don't count.
As a consequence, the only tests available are those that use fossil records to span the millenia involved in the evolution of "higher" species. But that, of course, brings us back to the rejection of such studies out of hand.
Genomic studies evidence a degree of commonality in genomes across species that makes it clear that common ancestors are involved. Creationists reject this as simply another piece of evidence of the elegance of God's creations.
Ultimately, one is left understanding that there is no purpose in arguing "science" with those whose ideas of truth are defined by their notions of revelation. In The Merchant of Venice, Shakespeare has Antonio say "The devil can cite Scripture for his purpose. An evil soul producing holy witness Is like a villain with a smiling cheek." The same might be said of Creationists claiming to quote "science."