Some of the crown jewels of Evolution are Ring Species. One of the hardest things for evolution to prove is that one species can actually become another species. Through Ring Species, biologists feel that they have uncovered actual evidence that this occurs. They have examples of salamaders turning into salamanders, and sea gulls turning into sea gulls.
That's the best they have for the whole "speciation" concept. It's their Crown Jewel.
Pathetic, huh?