Norops sagrei

Geographic Range

Brown anoles are found from southern Georgia and Florida to the southern tip of Mexico and the Caribbean. They are native to Cuba, the Bahamas (and surrounding islands), and throughout the Caribbean, as observed beginning in the late 1800's. About 50 to 60 years ago, they came to southern Florida and Mexico and more recently, they have appeared in and colonized Hawai'i and Jamaica. Brown anoles were most likely introduced to these areas by escapes made by pets and as stowaways on planes and ships. They have most recently spread to southeastern states such as Georgia, with one isolated population even sighted in the Houston, Texas area. Georgia brown anoles were most likely brought there by hitching rides on vehicles transporting landscaping plants and on boats (i.e. up interstate highways).

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native
• neotropical neotropical
  • native native
• oceanic islands oceanic islands
  • introduced introduced

Habitat

The brown anole is a "trunk-ground" terrestrial species, concentrated in areas with open vegetation as well as moist forested areas. However, at times, it can occupy the higher niches in trees, placing the species in the "tree-crown" dweller category as well. It enjoys a semi-tropical environment with a humidity of between 40-80% and a comfortable temperature of 75-80 degrees Fahrenheit (23.8-26.6 C), with a minimum temperature of 65 degrees Fahrenheit (18.3 C). The brown anole forms its territory among shrubs, vines, fences, and trees.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• scrub forest scrub forest

• Other Habitat Features
• urban urban
• suburban suburban

Physical Description

Norops sagrei is medium-sized, quite robust with a short and wide head, and is covered in small scales. It has a notably short snout compared to other anoles , long claws and a long tail. Its long toes and reduced toe-pad surface area help the brown anole to run and jump. Furthermore, its feet pads contain millions of microscopic fibers that allow it to attach to almost any kind of surface, whether smooth as glass or textured. The brown anole is sexually dimorphic, with the males exceeding the females in size. Mature adult males are generally 54 mm in snout-to-vent length (SVL) and weigh 6-8 grams, where mature adult females are generally 43 mm SVL and weight 3-4 grams. Male coloration varies highly, from light grey to stark-black and from a uniform color to multiple colorations (covered dorsally with irregular dark patches and a light-colored network of lines outlining the patches). Female coloration covers a wide range as well, however, they almost always have a dorsal white stripe with a dark triangular pattern that is very recognizable as a female brown anole trait. The most recognizable feature of the male brown anole is its dewlap. This is a "throat fan" that the male can extend to reveal an orange-red color display for territorial and courtship purposes. Females also have much smaller versions of the dewlap, but they do not use them. The brown anole can be distinguished from its relative species, the native green anole ( Anolis carolinensis ), because the green anole has a much longer, pointed snout, its coloration is green (although it can change colors like a chameleon in response to environmental or physiological changes), and its dewlap is a recognizably lighter pink shade.

• Other Physical Features
• heterothermic heterothermic

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful
• ornamentation ornamentation

Development

Norops sagrei follows typical lizard development from an egg to a juvenile to an adult. Hatchlings are 15-18 mm long (snout to vent). and are usually seen in early June. They are independent at birth, very conspicuous and fast developers. Brown anole hatchlings will reach sexual maturity before their first breeding season, the following summer (at approximately 1 year old).

Reproduction

Little research is available on the brown anole for its mating system, however there is research available in this area on its close relative, the green anole ( Anolis carolinensis ). The green anole exhibits "female-defense polygyny" which is when the male patrols the outskirts of the females' territories that he will mate with in order to keep other males away. The number of females per male is usually a few females to every one male. The female moves to where the male can see her when she is ready to breed. She signals the male to approach by cocking her neck so the male can grab on with his mouth. These are brief encounters (1-2 minutes) when the male makes the final decision if he will copulate with her or not. Seventy percent of the time the male lets go of the female to search for a suitable mate. When copulation does occur, it usually lasts between 30 and 60 minutes. The female anole then finds the right spot in moist soil, mulch or leaf litter to dig a small hole and lay her egg (usually a single egg, sometimes two).

• Mating System
• polygynous polygynous

Most often, the adult brown anole breeds seasonally in the summer months (generally March or April until August or September). During this time, the female lays one or two eggs at a time on a weekly or bi-weekly basis for the entire breeding season. She generally lays between 15 and 18 eggs per breeding season. Such a short egg-laying period is possible due to the fact that she can alternate the use of her right and left ovaries. Females are also usually sexually active for a slightly longer period than males, because they can store sperm and continue to fertilize their own eggs after the normal breeding period ends for males. In order for the female to successfully lay her eggs, she must have moist soil or leaf-litter to lay them in and an environment high in humidity.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
• oviparous oviparous
• sperm-storing sperm-storing

Most anole research available pertaining to parental care was conducted on green anoles , a closely related species. After the female has deposited her egg, she covers it up and abandons the site. Further parental care is neither given nor necessary since the egg is hardy enough to survive and hatch on its own. The surface of brown anole eggs can be described as being covered with small, but recognizable, longitudinal marks. The egg(s) hatch 6-8 weeks later and the anole hatchlings are on their own. They must rely completely on instinct to catch food in order to survive.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female

Lifespan/Longevity

The brown anole can live up to of 5 years in the wild, and 8 years in captivity. Very few brown anoles live this long in the wild though, and the average lifespan in captivity is about 4 years.

Behavior

The brown anole is a diurnal, terrestrial species that is not generally aggressive except when under certain conditions during breeding season. It is communal, sharing a territory about the size of the area of a large bush. Female and male territories are separate, however, there are generally two or more female territories within one male territory. This living system may be explained by the Norops sagrei mating system, however we don't know for sure. It is clear through some studies however, that male Norops sagrei spend more time displaying their dewlaps and bobbing their heads in tandem with other brown anoles than with anoles of other species, suggesting they feel the necessity to emit a higher degree of threat to their closest potential competitors. This also suggests that species recognition by N. sagrei lizards is definitely present and protection of females by the males is part of their mating and behavior systems.

Individuals of this species sheds their skin several times a year (in flakes rather than large pieces), and is a very hardy and adaptable species. For example, there are approximately 250 different species in the genus Norops and closely related genus Anolis , all of which display diverse morphologies and behaviors, in relation to the specific environment they live in. There are base-of-tree specialists, arboreal specialists, tree-canopy specialists, grass specialists and trunk specialists. Respectively, trunk specialists have flatter bodies and shorter tails and canopy specialists have evolved more well-developed toe pads than the other specialists. The brown anole, being a base-of-tree specialist, often perches low on trees, fences, buildings or rocks, with its head down in a sit-and-wait posture. Most of the day is spent looking for food and basking in the sun. During the breeding season, males become extremely territorial and use their dewlap as a powerful display, to either ward off threatening males or attract potential female partners. The way the male does this, is by compressing his body, extending his colorful dewlap into a fan-like display, followed by him bobbing his head and doing "push-ups" to either attract the female or scare away the male. Females have a dewlap as well, however they do not use it. There does not appear to be a structured social hierarchy among this species, however the bigger the male and the bigger his dewlap, the more powerful he is in the social system when looking for mates and warding off males. N. sagrei has been known to fight much more among its own species than with other species, although it is not a considerably vicious animal.

• Key Behaviors
• arboreal arboreal
• terricolous
• diurnal diurnal
• sedentary sedentary
• territorial territorial
• social social

Home Range

Norops sagrei typically guard the small bushes they reside in against outsiders and other species.

Communication and Perception

The brown anole produces no audible sounds and therefore relies mostly on body language and physical appearance to communicate. The male knows that the female is ready to mate by the tilting of her head. The female knows when the male wants to mate when he displays his dewlap and bobs his head. Males communicate by their physical size, the smaller males will submit to the intimidation of the larger males and often back off, although mouth fights until death can occur between closely matched males.

These anoles perceive their environment via scent, sight, touch, and sound.

• Communication Channels
• visual visual
• tactile tactile

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Brown anoles eat a variety of foods. The most common prey are arthropods (i.e. amphipods , spiders , isopods and insects (including moths , crickets , beetles , flies , grasshoppers , and butterflies ), also other invertebrates such as earthworms and snails . Brown anoles also feed on small vertebrates, including the hatchlings of the green anole .

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• Animal Foods
• reptiles
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms

Predation

Hatchlings anoles are eaten by adults of other anole species. Although there is not much information on predators of the brown anole specifically, sources did note that adults are eaten by many vertebrates, such as broadhead skinks ( Eumeces laticeps ), snakes and some birds. Spiders can sometimes capture and eat small anoles.

The coloration of Norops sagrei is such that it can easily blend in with the bark of a tree or on brown earth, rendering it nearly invisible to predators.

This is an alert and quick-moving species of lizard, that sprints from predators if it can.

If captured, brown anoles have one notable anti-predator adaptation involving their tails. The anole can voluntarily break off and drop most of its tail when being pursued. The separated tail will twitch and flail around for a short time, which often distracts the predator and allows the tailless lizard to escape. The brown anole tail is cartilagenous and will slowly regenerate into a new tail, however the new tail is usually a dull gray and is often smaller than the original tail.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Anoles on islands may be significant predators of arthropods. Some experiments have shown that removing the lizards from islands results in increased populations of spiders, and reduced populations of other insects that are spider prey.

Since the brown anole was been introduced into southern Florida there has been a significant decline in the green anole population in rural and urban areas. The brown and green anoles are similar in size with simliar feeding habits. There is probably competition between the two related species in their habitat, as well as "intra-guild predation," meaning they eat each others' hatchlings. The full extent of the interactions between these two species, and the ecological effects of the invasion of brown anoles in southeastern North America is not known.

Economic Importance for Humans: Positive

This species eats pest species of arthropods, including cockroachs and spiders. It's not clear whether they eat enough of these to have a significant affect on the arthropod populations, but many people believe the do.

Humans may also benefit directly from pet trade, since the brown anole is popular among pet lizard owners.

• Positive Impacts
• pet trade pet trade
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse affects of Norops sagrei on humans, although some may consider this species abundance in urban areas a nuisance.

The introduced population of this species in mainland southeastern North America seems to be affecting the native species of anole there, but there doesn't seem to be any direct affect on human welfare.

Conservation Status

This abundant species is not believed to be in need of special conservation efforts.

Other Comments

The brown anole has become a model organism for the study of ecology, animal behavior, and evolution. A number of experiments have recently been performed where Norops sagrei has been introduced into an isolated area (i.e. an island) and natural selection has been observed. This research has been possible due to the fact that the brown anole species is very hardy, a good colonizer, a good adaptor, not an economic pest and it exhibits a high reproductive fitness rate. Anole lizards are found all over the islands of the Caribbean, living sympatrically, but exhibiting a vast array of different morophologies and behaviors. These types of differences have been identified among the same species on the same island, much like Darwin's finches of the Galapagos Islands and the lemurs of Madagascar. Anole lizards have adapted into every available niche. What is very unusual about Caribbean anoles, however, is that the same types of habitat specialists occur on each separate island. All of the islands contain anoles that share almost identical appearances, habitats and behaviors. The presence of similar species on different islands may be explained by an ancestral species that adapted to a specific niche and then made its way to the islands or an ancestral species that evolved at a time when the islands were still connected. Alternatively, each specialist may have arisen independently on each of the islands. Jackman, Larson and Queiroz studied this topic to discover which explanation is correct. They found that habitat specialists on one island were genetically more closely related to different specialists in the same habitat, rather that to similar specialists elsewhere. Therefore, these specialists seem to have evolved independently on each island. This evolution may also be studied through the fossil record, although the anole fossil record is scarce. Only about a dozen fossils of these lizards have been discovered, two of them dating back to the Miocene period (20 million years ago). Interestingly, these ancient specimens are almost identical to the tree-canopy habitat specialists that live today. The brown anole has allowed researchers to study evolution over a much shorter time period than it usually occurs. For example, the Schoeners introduced it to twenty islands to see if it would survive. The brown anole survived on all of the islands, except the smaller ones, and even flourished. The smaller islands could not support the new species since small islands are of lower elevations and therefore, more vulnerable to catastrophic events such as hurricanes. Because the islands had slightly different vegetation, the Schoners were able to witness evolution, as the anoles' morphology changed over generations, in direct relation to the specific environment. Lizard populations with broad perching surfaces (e.g. thick tree trunks), had longer legs than populations with narrow perching surfaces (grass and herb stems). These researchers have found that anoles are adaptable creatures that are living test cases for investigations into how evolution works.

Norops sagrei has also been classified in the genus Anolis .

Additional Links

Encyclopedia of Life

Contributors

David Armitage (editor), Animal Diversity Web, George Hammond (editor), Animal Diversity Web.

Matthew Wund (editor), University of Michigan-Ann Arbor.

Lauren Casanova (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

References

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Campbell, T. 2000. "The brown anole, Anolis sagrei" (On-line ). Institute for Biological Invasions Invader of the Month. Accessed March 19, 2003 at http://invasions.bio.utk.edu/invaders/sagrei.html .

Greenberg, N. 1992. "The Saurian Psyche Revisited: Lizards in Research" (On-line). Accessed August 26, 2004 at http://notes.utk.edu/bio/greenberg.nsf/0/c95b2abf95ee46ed85256a1d005affb4?OpenDocument .

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Losos, J. 2001. Evolution: A lizard's tale. Scientific American , 284(3): 64-69. Accessed April 8, 2003 at http://proquest.umi.com/pqdweb?Did=000000068501331&Fmt=3&Deli=1&Mtd=1&Idx=1&Sid=2&RQT=309 .

Losos, J., M. Leal. 1999. "Anolis Newsletter V" (On-line). Accessed August 27, 2004 at http://biosgi.wustl.edu/~lososlab/newsletter/newsletter.html .

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Mazzotti, F., C. Sekerak. 2001. "Lizards of South Florida Part 1: Native Species" (On-line ). University of Florida: Cooperative Extension Service Institute of Food and Agriculture Sciences. Accessed March 19, 2003 at http://edis.ifas.ufl.edu/BODY_UW061 .

Parmley, D. 2002. Northernmost record of the brown anole (anolis sagrei) in Georgia. Georgia Journal of Science , 60(4): 191-193.

Schoener, T., D. Spiller, J. Losos. 2001. Natural Restoration of the Species-Area Relation for a Lizard After a Hurricane. Science , 294(5546): 1525-1528.

Central Pets Educational Foundation. 2003. "Central Pets" (On-line ). the brown anole - Anolis sagrei. Accessed March 21, 2003 at http://www.centralpets.com/pages/critterpages/reptiles/lizards/LZD2653.shtml .

University of Texas College of Natural Sciences and Texas Memorial Museum at UT Austin. 1997. "Herps of Texas - Lizards" (On-line ). Anolis sagrei. Accessed March 19, 2003 at http://www.zo.utexas.edu/research/txherps/lizards/anolis.sagrei.html .

UNEP & WCMC. 2003. "UNEP-WCMC Species Database" (On-line). Accessed March 21, 2003 at http://sea.unep-wcmc.org/isdb/Taxonomy/ .