Are Darwin's Finches One Species or Many?

The finches that Charles Darwin collected in the Galapagos Islands are considered textbook examples of how a single species differentiated into many to exploit different resources. Subtle changes in the size and structure of beaks among the six species of ground finches have been called “evolution caught in the act.” But are they really one species, or several? In Science Smackdown, we let experts argue both sides of the question.