Urosaurus ornatus
Encyclopedia
The Tree lizard or Ornate Tree Lizard (Urosaurus ornatus) is a species
of lizard
that is native to the southwestern United States
and northern Mexico
. The species has been used to research the physiological changes in the body during the fight-or-flight response
as related to stress and aggressive competition. Also, its life history and costs of reproduction have been documented in field populations in New Mexico.
approximately two weeks after mating. In many parts of the Tree Lizard's range females may lay more than one clutch of eggs a year.
Male tree lizards come in a variety of colors. While not all populations of tree lizards contain more than one or two colors, nine color types have been documented within Urosaurus ornatus. A population documented in Verde River, Arizona, has two types of coloration patterns among male tree lizards that account for 45 percent of all males. The first is characterized by a blue spot in the center of a larger orange spot on the chin, a throat fan that is orange by the body and blue at the tip, and a blue stomach. The second is orange in coloration: the chin is solid orange, as is the throat fan and the stomach. The orange-blue males are more aggressive and defend territories that can include up to four female tree lizards. The orange males have a longer, leaner body type and are not aggressive. Orange males can be nomadic during dry years, and during rainy years tend to occupy small territories.
Some, such as Stanford professor and biologist Joan Roughgarden
, have suggested that in this species there are multiple male genders. Among differently colored male tree lizards, there are different hormonal profiles. On the day a male tree lizard hatches, an abundance of progesterone
will cause him to develop into an orange-blue type. Low progesterone will lead to the male developing into an orange type. During dry weather conditions, orange-type males' corticosterone
levels increase, which causes testosterone
to decrease, which leads to their instinct to become nomadic. Likewise, orange-blue types do not have this hormonal response to the weather, and remain in their territory regardless of climatic conditions.
: California
, Nevada
, Utah
, Colorado
, Wyoming
, Arizona
, New Mexico
, and Texas
.
Mexico
: Sonora
, Sinaloa
, Chihuahua, and Coahuila
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
that is native to the southwestern United States
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
and northern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. The species has been used to research the physiological changes in the body during the fight-or-flight response
Fight-or-flight response
The fight-or-flight response was first described by Walter Bradford Cannon....
as related to stress and aggressive competition. Also, its life history and costs of reproduction have been documented in field populations in New Mexico.
Reproduction
A group consisting of one male and one or more females typically inhabit an area that contains one or more large tree or shrub. The male copulates with each female and the female deposits eggsEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
approximately two weeks after mating. In many parts of the Tree Lizard's range females may lay more than one clutch of eggs a year.
Male tree lizards come in a variety of colors. While not all populations of tree lizards contain more than one or two colors, nine color types have been documented within Urosaurus ornatus. A population documented in Verde River, Arizona, has two types of coloration patterns among male tree lizards that account for 45 percent of all males. The first is characterized by a blue spot in the center of a larger orange spot on the chin, a throat fan that is orange by the body and blue at the tip, and a blue stomach. The second is orange in coloration: the chin is solid orange, as is the throat fan and the stomach. The orange-blue males are more aggressive and defend territories that can include up to four female tree lizards. The orange males have a longer, leaner body type and are not aggressive. Orange males can be nomadic during dry years, and during rainy years tend to occupy small territories.
Some, such as Stanford professor and biologist Joan Roughgarden
Joan Roughgarden
Joan E. Roughgarden is an American evolutionary biologist.- Biography :...
, have suggested that in this species there are multiple male genders. Among differently colored male tree lizards, there are different hormonal profiles. On the day a male tree lizard hatches, an abundance of progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
will cause him to develop into an orange-blue type. Low progesterone will lead to the male developing into an orange type. During dry weather conditions, orange-type males' corticosterone
Corticosterone
Corticosterone is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands.-Roles:In many species, including amphibians, reptiles, rodents and birds, corticosterone is a main glucocorticoid, involved in regulation of fuel, immune reactions, and stress...
levels increase, which causes testosterone
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...
to decrease, which leads to their instinct to become nomadic. Likewise, orange-blue types do not have this hormonal response to the weather, and remain in their territory regardless of climatic conditions.
Taxonomy
- Texas Tree Lizard, Urosaurus ornatus ornatus (BairdSpencer Fullerton BairdSpencer Fullerton Baird was an American ornithologist, ichthyologist and herpetologist. Starting in 1850 he was assistant-secretary and later secretary of the Smithsonian Institution in Washington, D.C...
& GirardCharles Frédéric GirardCharles Frédéric Girard was a French biologist specializing in ichthyology and herpetology.Born in Mulhouse, France, he studied at the College of Neuchâtel, Switzerland as a student of Louis Agassiz. In 1847, he accompanied Agassiz as his assistant to Harvard...
, 1852) - Urosaurus ornatus caeruleus (SmithHobart M. SmithHobart Muir Smith, born Frederick William Stouffer , is an American herpetologist. He was born in Stanwood, Iowa, United States. He has been credited with describing several new species of North American reptiles and amphibians...
, 1935) - Urosaurus ornatus chiricahuae (Mittleman, 1941)
- Urosaurus ornatus lateralis (BoulengerGeorge Albert BoulengerGeorge Albert Boulenger FRS was a Belgian-British zoologist who identified over 2000 new animal species, chiefly fish, reptiles and amphibians.-Life:...
, 1883) - Smooth Tree Lizard, Urosaurus ornatus levis (StejnegerLeonhard Hess StejnegerLeonhard Hess Stejneger was a Norwegian-born American ornithologist, herpetologist and zoologist. Stejneger specialized in vertebrate natural history studies. He gained his greatest reputation with reptiles and amphibians....
, 1890) - Lined Tree Lizard, Urosaurus ornatus linearis (BairdSpencer Fullerton BairdSpencer Fullerton Baird was an American ornithologist, ichthyologist and herpetologist. Starting in 1850 he was assistant-secretary and later secretary of the Smithsonian Institution in Washington, D.C...
, 1859) - Big Bend Tree Lizard, Urosaurus ornatus schmidti (Mittleman, 1940)
- Schott's Tree Lizard, Urosaurus ornatus schottii (BairdSpencer Fullerton BairdSpencer Fullerton Baird was an American ornithologist, ichthyologist and herpetologist. Starting in 1850 he was assistant-secretary and later secretary of the Smithsonian Institution in Washington, D.C...
, 1858) - Colorado River Tree Lizard, Urosaurus ornatus symmetricus (BairdSpencer Fullerton BairdSpencer Fullerton Baird was an American ornithologist, ichthyologist and herpetologist. Starting in 1850 he was assistant-secretary and later secretary of the Smithsonian Institution in Washington, D.C...
, 1858) - Northern Tree Lizard, Urosaurus ornatus wrighti (SchmidtSchmidtSchmidt may refer to:* Schmidt , including list of people with the surname* Schmidt * Schmidt , a crater on Mars* Schmidt , in Kamchatka...
, 1921)
Geographic range
United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
: California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, and Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
.
Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
: Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
, Sinaloa
Sinaloa
Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....
, Chihuahua, and Coahuila
Coahuila
Coahuila, formally Coahuila de Zaragoza , officially Estado Libre y Soberano de Coahuila de Zaragoza is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico...
.