The Galapagos Land Iguana was studied by Charles Darwin early in the 19th Century. Darwin observed this species' similarity to iguanas on the South American mainland, as well as its adaptations to its island environment. These observations along with those of various other species, lead to Darwin developing his theory of evolution. This species feeds primarily on prickly pear cactus fruits and leaves. The Galapagos land iguana was formerly widely distributed throughout the island chain but numbers are now greatly reduced due to introduction of invasive predator species and over hunting and collecting.