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|Carolina anole with dewlap extended|
The Polychrotidae are a family of lizards commonly known as anoles (pron.: //). NCBI places the anole in subfamily Polychrotinae of the family Iguanidae. Four genera are common: Anolis, Norops, Phenacosaurus, and Polychrus.
Due to their ability to change color, anolis (anole) lizards are frequently referred to as American chameleons. Also, because they can run up walls, they are sometimes confused with geckos. They are not closely related to either of those groups and, in fact, are more closely related to iguanas.
Characteristics and distribution 
Anoles are small and common lizards that can be found throughout the southeastern United States and at least as far west as San Antonio, the Caribbean, and various other regions of the Western world. A large majority of them sport a green coloration, including the only species native to North America, the aptly named green anole, although the green anole can change its color based on its mood and surroundings. Anoles are an exorbitantly diverse and plentiful group of lizards. About 372 species are known. The knight, green, bark, Jamaican giant, and Cuban brown anoles can all be found in the United States, primarily in Florida, although the most prevalent of these species by far is the Cuban brown anole, which has pushed the native green (or "Carolina") anole population farther north.
Interestingly, when green anoles and brown anoles inhabit the same area, the brown anoles are primarily terrestrial or restrict themselves to the lower branches of bushes, while the green anoles stay higher. Brown anoles have also spread into East Texas. At a nursery in the Heights neighborhood of Houston, Texas, a stable population has established itself, hatchlings having been observed in the spring of 2005.
All species of anole in the US except the green anole were introduced through eggs nested in imported plants. While nearly all anoles can change their color, the extent and variations of this ability differ widely throughout the individual species. For example, the green anole can change its color from a bright, leafy green to a dull brown color, while the Cuban brown can only change its shade of brown, along with the patterns on its back.
Many anoles are between eight and 18 cm (3–7 in) in length. Some larger species, such as the knight anole, can surpass 12 in (300 mm); some males of the knight anole species can even reach 20 in (510 mm) in length.
Anoles' diets include live insects and other invertebrates, with crickets, spiders, and moths being some of the most commonly consumed prey. They have been seen to eat butterflies. Anoles are opportunistic feeders, and may attempt to eat any attractive meal that is small enough. The primary foods for captive anoles are small feeder crickets that can be purchased at most pet stores.
These subtropical lizards are semiarboreal. They usually inhabit regions around 3–6 m (10–20 ft) high. Shrubs, walls, fences, bushes, and short trees are common hiding places.
Most anoles are said to live between four and eight years. Even anoles captured from the wild can live for several years if given acceptable living space and cared for properly; a healthy anole in captivity, being free from predators and natural disaster, may live well beyond seven years. Some anoles may even reach 14 years with careful and proper care.
Breeding occurs for several months beginning in late spring. Males employ head bobbing and dewlap extension in courtship. One or two small, soft-shelled eggs are laid among leaf litter. More clutches may be laid before mating season has ended.
Anoles have many readily identifiable features. They have dewlaps, made of erectile cartilage, that extend from their neck/throat areas. Their toes are covered with structures that allow them to cling to many different surfaces. Also, their tails have the ability to break off at special segments to escape predators or fights. The tail continues to wriggle strongly for some minutes after detaching. This ability is known as autotomy. Anoles are also diurnal - active during the daytime.
Some species of anoles exhibit sexual dimorphism, which allows one to discern between males and females fairly easily with the naked eye. In green anoles, the female is characterized by a pale dorsal stripe extending from the neck to the tail, a generally smaller body, and a smaller head with a shorter snout. Female brown anoles share these characteristics, although their dorsal stripes are often wider, with diamond-shaped or squiggly edges. This stripe may be present sometimes in males, especially young ones not yet fully grown, but it is always fainter with less-defined edges. Some females have small dewlaps (pale and much smaller than those of the males).
Evolution and adaptability 
On the website Anole Annals, Martha Munoz calls attention to a 2012 paper ("Rapid Change in the Thermal Tolerance of a Tropical Lizard") by scientists Alex Gunderson and Manuel Leal of Duke University, in which they examine whether physiology has evolved in the invasive populations of Anolis cristatellus (the Puerto Rican crested anole) in Florida, which "is actually much colder than Puerto Rico":
Anolis lizards are a model system for studies of evolutionary ecology because they are remarkably adaptable creatures. We know from long-term studies...that anoles can rapidly adapt their behavior and morphology over ecological timescales. For example, the presence of a ground-dwelling predator (Leiocephalus carinatus) forged a strong selective gradient in favor of A. sagrei with longer hindlimbs within a single generation. Interestingly, in a follow-up study the long-term effect of this predator is that A. sagrei evolves shorter hindlimbs, as they will tend to perch higher off the ground, where the perch diameter is narrower than near the ground. ...
A notable exception to Anolis 'evolvability,' however, is thermal physiology... Although native to the balmy isle of Puerto Rico, A. cristatellus has made a permanent home in Florida... In a previous study, Jason Kolbe and colleagues demonstrated that the thermal niches (i.e., available thermal habitat) are quite divergent between Puerto Rico and Florida, and showed a rapid evolutionary response in acclimation to thermal environment in one of the invasive populations. This sets up the possibility that invading anoles will evolve their thermal physiology to match their new environment...[A]lthough thermal physiology is predominantly conserved among lizards, anoles are a notable exception to this rule.
Anole populations in each of the Martinique islands, despite remaining separate for an estimated six to eight million years, have not experienced significant evolution, and many mixed-island couples have successfully reproduced.
Anoles are very territorial. Although the lizards can grow up to 7 inches in a habitat, their territories are usually quite small: around three square yards, with females' usually smaller. Their territories often contain a basking area, a shady area, a high lookout, and always a place to hide from predators. They do not tolerate other anoles in their territory. Often, when an intruder is in the area, the anole raises its spine, fans its dewlap, and does "push-ups" accompanied by intermittent ultrasonic hisses. If this does not scare off the intruder, a fight proceeds in which the two anoles bite at each other's tails. If the anole loses (gives up) the intruder gains entrance, otherwise he leaves. Females rarely fight. Anoles have a wide range of territorial behavior from one head bob to a pressurized bite usually aimed for the snout or jaw of the lizard.
Relationship with humans 
Anoles function well as a native pest control, as they will eat spiders, cockroaches, and other bugs and most will run from humans when possible, but some are aggressive enough to bite an imposing hand.
When caught by a person, they will tend to bite if agitated and require some effort to remove from skin. They very infrequently draw blood or cause injury.
At least eight species of non-native anoles have been introduced to Florida and other parts of the southeastern United States by humans, including the brown anole. The Puerto Rican crested anole has also been introduced beyond its native range to other Caribbean islands, where it may outcompete the indigenous species.
- NCBI Taxonomy Browser
- Losos, Jonathan (May 10, 2011). "They Don't Eat Butterflies, Do They?". Anole Annals. Retrieved November 19, 2012.
- Munoz, Martha (Posted on November 16, 2012). "Physiological Adaptation On Ecological Timescales – New Research by Alex Gunderson and Manuel Leal". Anole Annals. Retrieved November 18, 2012.
- "How Important Is Geographical Isolation in Speciation?". ScienceDaily. May 1, 2010. Retrieved May 6, 2010.
- Meshaka, W. E. 2011. "A Runaway Train in the Making: The Exotic Amphibians, Reptiles, Turtles, and Crocodilians of Florida" in Herpetological Conservation & Biology 6:1-101. http://herpconbio.org/Volume_6/Monograph_1/Meshaka_2011.pdf
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