Galapagos land iguana

Description

The Galápagos land iguana (Conolophus subcristatus) is a species of lizard in the family Iguanidae. It is one of three species of the genus Conolophus. It is endemic to the Galápagos Islands (Ecuador), in the dry lowlands of Fernandina, Isabela, Santa Cruz, North Seymour, Baltra, and South Plaza Islands. The land iguanas in the Galápagos vary in morphology and coloration among different populations. In addition to the relatively widespread and well-known Galápagos land iguana (C. subcristatus), there are two other species of Conolophus: the Galápagos pink land iguana (C. marthae) from northern Isabela Island and the Santa Fe land iguana (C. pallidus) from Santa Fe Island. Based on mtDNA, the land iguanas and marine iguana diverged about 8–10 million years ago. Within the land iguana genus, the oldest split based on mtDNA, about 5.7 million years old, is between C. subcristatus and C. marthae. A more recent study that included both mtDNA and nuclear DNA indicates that the land iguanas split from the marine iguana about 4.5 million years ago, and among the land iguanas C. subcristatus and C. marthae split from each other about 1.5 million years ago. The differentiation between the last two species, C. subcristatus and C. pallidus, is less clear and it has been questioned whether they are separate species. Based on mtDNA and cytochrome b, they fall into three monophyletic groups: C. subcristatus of western islands (Isabela and Fernandina), C. subcristatus of central islands (Santa Cruz, Baltra and South Plaza) and C. pallidus. Although the exact pattern is uncertain, it is possible that C. pallidus is closer to one of the C. subcristatus groups than the two C. subcristatus groups are to each other. Its specific name subcristatus is derived from the Latin words sub meaning "lesser" and cristatus meaning "crested", and refers to the low crest of spines along the animal's back, which is not as tall as in most iguanas. Galápagos land iguanas become sexually mature anywhere between eight and fifteen years of age, depending on which island they are from. Mating season also varies between islands, but soon after mating, the females migrate to sandy areas to nest, laying 2–20 eggs in a burrow about 50 cm (20 in) deep. The eggs hatch anywhere from 90 to 125 days later.