Evolutionary anomalies, I think?

DNA doesn't decide anything. It's not intelligent. Something happens that causes it to create a mutation, that mutation either lives, or it dies. If it lives, then the mutation is passed on to it's descendents. The more of them that live, the more the mutation is spread. If it's successful then over the period of thousands or millions of years, you get a new species.

Look at the birds and other animals in Hawaii. They all started out a different species, but are all recognized as a unique species now, even though they look like their ancestors still. In time they'll look totally different.