On the islands of Hawaii, approximately 800 species of fruit flies have evolved from just one ancestral species in the 8 million or so years since that ancestor arrived. The heads, forelegs, wings, and mouthparts of different species all look and function very differently. These fruit flies are found nowhere else in the world and live all over the islands, from sea-level rainforests to higher altitude meadows. How could so many species have evolved from a single ancestral fruit fly species?