Does "distinction" refer to the distinction/differences between ...?

Does "distinction" refer to the distinction/differences between "major changes in biological function" and "microevolution"?
If so, what does "artificial" mean?

Context:

Most of those mutations occur in parts of the genome that are not essential, and therefore they have little or no conse-
quence. The ones that fall in the more vulnerable parts of the genome are generally harmful, and are thus rapidly culled out
of the population because they reduce reproductive fitness. But on rare occasions, a mutation will arise by chance that offers a slight degree of selective advantage. That new DNA "spelling" will have a slightly higher likelihood of being passed on to future offspring. Over the course of a very long period of time, such favorable rare events can become widespread in all members of the species, ultimately resulting in major changes in biological function.

In some instances, scientists are even catching evolution in the act, now that we have the tools to track these events. Some critics of Darwinism like to argue that there is no evidence of "macroevolution" (that is, major change in species) in the fossil record, only of "microevolution" (incremental change within a species). We have seen finch beaks change shape over time, they argue, depending upon changing food sources, but we haven't seen new species arise.

This distinction is increasingly seen to be artificial. For example, a group at Stanford University is engaged in an intense
effort to understand the wide diversity of body armor in stickle-back fish. Sticklebacks that live in salt water typically have a
continuous row of three dozen armor plates extending from head to tail, but freshwater populations from many different
parts of the world, where predators are fewer, have lost most of these plates.