How Do Species Evolve?

Islands are natural evolution laboratories. Castaways are rare, but once they arrive, they evolve into distinct new forms. Take Hawai'i's Hyposmocoma moths. Over millions of years, they've evolved into perhaps 500 separate species. As caterpillars, some Hyposmocoma species live only on fresh lava flows; others, like H. lignivora (left, pictured in December 2008), prefer dead tree bark. H. elegantula (right,) lives on bare rocks along the coast. "Even the tiniest islands here have [Hyposmocoma] species found nowhere else," marvels University of Hawai'i entomologist Daniel Rubinoff.
—Composite image by Patrick Schmitz/Rubinoff Lab