You are a time-traveling evolutionary biologist studying a particular species of tropical bird on an island off the coast of Madagascar. You travel 300,000 years into the past and observe that while the birds are a variety of colors (red, blue, yellow, green) most of them are blue. This same species of bird and the same mix of colors are found on the mainland. Assuming that all the birds are descended from an ancestral blue bird, where did the other colors come from?