Sean Carroll in The Smithsonian Magazine talks about how the alternative color forms of some animals are providing new insights into how animals adapt and evolve:
One of the most widespread phenomena in the animal kingdom is the occurrence of darkly pigmented varieties within species. All sorts of moths, beetles, butterflies, snakes, lizards and birds have forms that are all or mostly black. Perhaps most familiar are the dark big cats, such as the black leopard and black jaguar. These beautiful animals are often displayed in zoos as curiosities, but they also occur in the wild in significant numbers.