Green iguana

The green iguana (Iguana iguana), also known as the American iguana or the common green iguana, is a large, arboreal, mostly herbivorous species of lizard of the genus Iguana. Usually, this animal is simply called the iguana. The green iguana ranges over a large geographic area; it is native from southern Brazil and Paraguay as far north as Mexico.

A herbivore, it has adapted significantly with regard to locomotion and osmoregulation as a result of its diet. It grows to 1.7 m (5.6 ft) in length from head to tail, although a few specimens have grown more than 2 m (6.6 ft) with bodyweights upward of 9 kg (20 lb).

Commonly found in captivity as a pet due to its calm disposition and bright colors, it can be very demanding to care for properly. Space requirements and the need for special lighting and heat can prove challenging to the hobbyist.

The species was first officially described by Swedish botanist Carl Linnaeus in 1758. Since then, numerous subspecies have been identified, but later classified as merely regional variants of the same species.

Using nuclear and mitochondrial DNA-sequence data to explore the phylogenic history of the green iguana, scientists from El Salvador, Mexico, and the United States studied animals collected from 17 countries. The topology of phylogeny indicated that the species originated in South America and eventually radiated through Central America and the Caribbean. The study revealed no unique mitochondrial DNA haplotypes for subspecific status, but did indicate the deep lineage divergence between Central and South American populations.

Naturalists once classified the Central American iguanas as a separate subspecies (I. i. rhinolopha), but this classification was later found to be invalid based on mitochondrial DNA, and iguanas with similar nose projections appeared randomly in other populations and interbred freely with those that do not share this trait. Genetic studies in the late 2010s still recovered I. rhinolopha as a distinct species, along with several other cryptic lineages present in I. iguana, and classifying only the South American populations may be the "true" green iguana. Two new insular subspecies (I. i. insularis and I. i. sanctaluciae) endemic to St. Lucia, Saint Vincent and the Grenadines and Grenada were also identified in 2019; a 2020 study also recovered both these subspecies as part of a distinct species, the southern Antillean horned iguana (I. insularis). The study also found the Saban black iguana (I. melanoderma), described in that study, to be the sister group of South American I. iguana, with the clade containing both being sister to that of I. insularis. The Reptile Database disagrees with these conclusions, and groups all of these within the green iguana, with four subspecies: I. i. melanoderma, I. i. insularis, I. i.sanctaluciae, and I. i. iguana.

The word "iguana" is derived from a Spanish form of the Taíno name for the species: iwana. In some Spanish-speaking countries, males of the species are referred to as garrobo or ministro and juveniles are called iguanita or garrobito.

The native range of the green iguana extends from southern Mexico to central Brazil, Paraguay, and Bolivia and the Caribbean; specifically Grenada, Aruba, Curaçao, Bonaire, Trinidad and Tobago, St. Lucia, St. Vincent, Montserrat, Saba and Útila. They have been introduced to Grand Cayman, Puerto Rico, Hispaniola (in the Dominican Republic side), Saint Martin (island), Guadeloupe, Martinique, Saint Vincent and the Grenadines, Singapore, Thailand, Taiwan, Texas, Florida, Hawaii, and the U.S. Virgin Islands. Furthermore, green iguanas colonised the island of Anguilla in 1995 after being washed ashore following a hurricane, serving as direct proof of the mechanism of oceanic dispersal in allowing species to colonise areas where they previously did not occur. Though the species is not native to Martinique, a small wild colony of released or escaped green iguanas endures at historic Fort Saint Louis.