Urosaurus ornatus
Urosaurus ornatus | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Iguania |
Family: | Phrynosomatidae |
Genus: | Urosaurus |
Species: | U. ornatus
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Binomial name | |
Urosaurus ornatus | |
Synonyms[2] | |
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Urosaurus ornatus, commonly known as the ornate tree lizard, is a species of lizard in the family Phrynosomatidae. The species is native to the southwestern United States and northwestern Mexico. The species, which was formerly called simply the "tree lizard", has been used to study physiological changes during the fight-or-flight response as related to stress and aggressive competition.[3][4] Its life history and costs of reproduction have been documented in field populations in New Mexico and Arizona.[5][6] This species has been fairly well studied because of its interesting variation in throat color in males (within a population) that can correlate with different reproductive strategies,[7][8]
Appearance
The ornate tree lizard may grow to a
Hierarchies
The differences in throat color can impact many different behaviors and create
Multiple male genders
Some, such as Stanford professor and biologist Joan Roughgarden, have suggested multiple male genders in this species. Among differently colored male tree lizards, there are different hormonal profiles. On the day a male tree lizard hatches, researchers think that high blood levels of progesterone and then later, as a juvenile, higher testosterone levels will cause him to develop into an orange-blue type; low progesterone and later lower testosterone levels, as a juvenile, may lead the male to develop into an orange type.[16] During dry weather conditions, orange-type males' corticosterone levels increase, which causes testosterone to decrease, leading them to be more likely to leave their territory and become nomadic. Orange-blue males do not have this hormonal response to the weather, and remain in their territories regardless of climatic conditions.[13]
Speed and stamina
The differences in throat color can also be related to speed and stamina in male lizards. OB males or dominant males are significantly faster than O males and have higher lengths of stamina than O males.[17] The link between social hierarchy and locomotor performance can be traced to the suite of displays that identify a dominant individual being the presence/size of the blue spot on their throats. These activities may be affected by different intensities and duration and it is possible for an O male to have better speed and stamina than an O male, it is just uncommon. The OB male having territorial and defensive traits makes them spend more time fighting or displaying and asserting their dominance over the O lizards and exerting that amount of physical strength allows them to develop the higher rates of speed and longer durations of stamina.[17] When the O male competes against the OB male and loses, the O male does not get the opportunity to utilize their speed and stamina and therefore causes them to have decreased rates of speed and shorter periods of stamina.
Significance of throat color
The throat color of this lizard represents important information about their level of
Additionally, throat coloration is also associated with size. 82% of hatchlings develop an orange throat color within 15 days of hatching and the lizards that had a delayed onset of throat coloration are typically smaller for their age. Therefore, the size of the ornate tree lizard is a better indicator of their throat color than their age.[18]
Population structure
Urosaurus ornatus has a complicated social hierarchy causing O males and OB males to fight for resources. The social systems that allow for the stability of the lizard population cause a mixed evolutionary stable strategy for the continuation of their genes. In a mixed evolutionarily stable strategy, both morphs pursue different life history strategies that allow them to achieve equal fitness. O and OB males behave differently in different situations, but most times having the OB male be dominant over the O male. While OB males are more dominant socially, O males are usually larger and grow faster than OB males, both in captivity and in the wild.[14] O males will reach a larger size before breeding time, but once both O and OB males reach adulthood they are the same size.[14]
Effects of habitat
Lizards are ectotherms and because of their temperature dependent lifestyle they may not follow predictions of density‐dependent habitat selection models because temperature strongly influences their habitat selection and population structure. Since competition for resources can cause a decrease in fitness, increased population size should cause a decrease in body size and growth rates across the population. In these lizards there is population density-dependent growth for females of this species but not for males. The temperature quality of the environment that these lizards live in also determines body size and composition. Lizards that are raised and produced in crowded spaces and environments with poor resources and lower temperatures grow smaller than lizards in higher quality environments with better suited temperatures and good resources.[19]
It has been suggested that the abundance of rainfall that the ornate tree lizard experiences induce a multitude of changes in this lizard's behaviors. During a four-year study in the grapevine hills of
Geographic range
Urosaurus ornatus is one of the most widespread and abundant of North American lizards. It inhabits a wide range of states throughout the United States, including California, Nevada, Utah, Colorado, Wyoming,[21] Arizona, New Mexico, and Texas.[22] It is arboreal, semi arboreal, or saxicolous throughout its wide living range and habitats. It can also be found in areas in Mexico including states such as Sonora, Sinaloa, Chihuahua, and Coahuila.
There are large temperature ranges throughout the southwestern United States and these lizards adapt to the different climates that they live in. Their mean body temperatures also change depending on where they are located. If the male lizard was in a montane habitat or a desert habitat their body temperature would be 35 degrees Celsius, but if the male lizard was in a desert riparian habitat its body temperature would be around 38 degrees Celsius.[23] Their changes in body temperatures reflect the climates they live in. These temperature differences also occur between male and female lizards. On average the body temperature of a female is lower than the males body temperature. There is a possibility that this difference in body temperature could be related to the presence or absence of sexual differences between males and females and could also affect the health of the clutch and the size of the clutch.
Size
The size of each lizard is closely related to their age and the seasonal state of their environment. During winter months (January through March), 75% of adults and 25% of juveniles are active and 13% of juveniles are active in the spring season. Additionally, at the beginning of April, 87% of the ornate tree lizards are in a reproductive state. This is because the beginning of April marks the beginning of their
Growth
The lizards will reach their minimum adult size within a year. Male ornate tree lizards will grow approximately 0.16 to 0.29 mm per month. During the spring and summer seasons, however, the male growth rate increases to an average of 2.1 mm per month. Female ornate tree lizards are typically smaller than males when they reach
Locomotion
These lizards tend to be active during every month except December. Both male and female ornate tree lizards emerge only on the warmest days in November and January, however, they engage in extended period of activity in February. When the lizards are active, they tend to occupy open locations in small or large boulders.[24]
Anti-predator behavior
Male Usosaurus ornatus lizards express chemical and behavioral responses to predators. Chemical responses of the males when encountering a predator can include changes in their levels of
The differences in
Diet
The ornate tree lizard feeds on mostly insects and their larvae, but have also been known to eat plants and vegetables as well as inanimate objects thinking they were food. These lizards also have diet patterns that change throughout the seasons changing what they eat and the quantity of it. In the winter/spring time their main food sources and largest quantity of food eaten were from the insect families Homoptera, Formicidae, Hemiptera, and Lepidopterous larvae but in the summer their diet changed to their main food sources mostly consisting of the insect families Coleoptera and Formicidae.[26] For the ornate tree lizard, their food intake is variable. Multiple studies have provided evidence that the diet of the Urosaurus ornatus is seasonally variable—the diet changes according to changes in the seasons. Because they are abundant in areas where there are more trees, they depend on the food available in that niche. When the seasons undergo change or the prey migrate, it induces changes in the abundance of the lizards food and its availability.[27]
Reproduction
A group of U. ornatus, consisting of one male and one or more females, typically inhabits an area containing one or more large trees, shrubs, or boulders. The male copulates with each female, and the females retain
Female reproduction
There is a direct correlation between the size of the female lizard and the size of the clutch that is produced. As body size increases the clutch size increases as well, making the bigger female lizards have a higher fitness due to size rarity. Body size for the female lizard could be a sought after trait and could be a factor in sexual selection and choosing a mate, a male may go after a larger female knowing that they will produce a larger number of offspring which will help them carry on their genes. There is also a relationship between the environment that the clutch is hatched in and the size of the clutch. Females that lay eggs in wet years tend to have a higher clutch size than females that lay eggs in the dryer years. This is due to temperature dependent reproduction and the effects the environment has on the reproductive process. The optimized temperature for the clutch to reach its maximum size comes with the temperatures associated with the dry season when reproducing.
Reproducing female ornate tree lizards are generally pregnant between late March through August. Additionally, they produce around two to seven eggs in their clutch once a year. The mean clutch size, however, is variable. The size of a female's clutch varies according to the season, and it will vary according to the geographical location of the female lizard. The latitude the reproducing female inhabits will change in the reproductive outcomes of the females. All the female's
Male reproduction
During the months of June through to November, male ornate tree lizards have enlarged testes when they reach sexual maturity. When the males emerge in January, they will have small testes, however, their mean testis size becomes progressively larger between the months of February, March, and April. By April, their testis size will level off and by June, the males will generally reach their largest testes size. By July, their testes size will slightly decrease and by August and September, their testes will rapidly decrease.[28]
Resource allocation for reproduction
When resources become scarce for the ornate tree lizard, this species encounters a multitude of critical challenges. There is direct competition between the female lizard's reproductive system and immune system for resources. When the amount of food intake is manipulated for reproducing female ornate tree lizards, there are changes in their allocation of resources in their bodies. When females have unlimited access to food intake, their reproductive systems and immune systems were readily maintained and healthy. This is because these females can invest more of their energy into reproduction and towards their immune systems. Therefore, these females can reproduce while simultaneously healing any wounds that they have on their bodies. When the females are on a restrictive diet, they experience changes in their reproductive and immune functions. If these reproducing females must invest energy into their reproductive and immune systems, there is a tradeoff. Therefore, these females have smaller follicles than the non-wounded females. When the females, however, are denied access to any food (extreme food restriction), they do not invest any energy towards their reproductive or immune systems. [29] Therefore, these females are influenced by resource competition between their reproductive and immune systems. This competition, however, only manifests itself when there are limited resources, and the intensity of this tradeoff depends on the abundance of resources. Since the abundance of resources is
Territoriality
Territoriality is an important part of reproduction for many males in this species. Males often defend territories by aggressively excluding other males. This aggression can, in part, be enhanced with higher levels of the steroid hormones testosterone and progesterone.[30] Females have home ranges but they do not defend territories. When the number of females on a male's territory is experimentally reduced by removing the females, the male is more likely to abandon his territory.[31]
Phenotype and reproduction
Females also can vary in throat coloration, although this is not as well-studied. When
Subspecies
Ten
- U. o. ornatus (Baird & Girard, 1852) – Texas tree lizard
- U. o. caeruleus (H.M. Smith, 1935)
- U. o. chiricahuae (Mittleman, 1941)
- U. o. lateralis (Boulenger, 1883)
- U. o. levis (Stejneger, 1890) – smooth tree lizard
- U. o. linearis (Baird, 1859) – lined tree lizard
- U. o. schmidti (Mittleman, 1940) – Big Bend tree lizard
- U. o. schottii (Baird, 1858) – Schott's tree lizard
- U. o. symmetricus (Baird, 1858) – Colorado River tree lizard
- U. o. wrighti (Schmidt, 1921) – northern tree lizard
Etymologies
The subspecific name, schmidti, is in honor of American herpetologist Karl P. Schmidt.[34]
The subspecific name, schottii, is in honor of German-American naturalist Arthur Carl Victor Schott.[34]
The subspecific name, wrighti, is in honor of American herpetologist Albert Hazen Wright.[34]
References
- . Retrieved 11 November 2021.
- ^ a b "Urosaurus ornatus ". The Reptile Database. www.reptile-database.org.
- S2CID 40870214.
- ^ Jennings DH, Moore MC, Knapp R, Matthews L, Orchinik M (2000). "Plasma steroid-binding globulins mediate stress reactivity in the tree lizard, Urosaurus ornatus ". General and Comparative Endocrinology 120: 289-299.
- S2CID 3226827.
- ^ French SS, Moore MC (2008). "Immune function varies with reproductive stage and context in female and male tree lizards, Urosaurus ornatus ". General and Comparative Endocrinology 155 (1): 148-156.
- ^ a b Hews DK, Thompson CW, Moore IT, Moore MC (1997). "Population frequencies of alternative male phenotypes in tree lizards: geographic variation and common-garden rearing studies". Behavioral Ecology and Sociobiology 41: 371-380.
- ^ Moore MC, Hews DK, Knapp R (1998). "Hormonal control and evolution of alternative male phenotypes: generalizations of models for sexual differentiation". American Zoologist 38: 133-151.
- ^ "Ornate Tree Lizard (Urosaurus ornatus) - Reptiles of Arizona".
- ^ Stebbins RC (2003). A Field Guide to Western Reptiles and Amphibians. (Peterson Field Guides). 3rd Edition.
- ^ Thompson CW, Moore MC (1991). "Syntopic occurrence of multiple dewlap color morphs in male tree lizards, Urosaurus ornatus ". Copeia 1991 (2): 493-503.
- ^ Thompson CW, Moore MC (1991). "Throat colour reliably signals status in male tree lizards, Urosaurus ornatus ". Animal Behaviour 42 (5): 745-753.
- ^ a b Knapp R, Hews DK, Thompson CW, Ray LE, Moore MC (2003). "Environmental and endocrine correlates of tactic switching by non-territorial male tree lizards, Urosaurus ornatus ". Hormones and Behavior 43: 83-92.
- ^ S2CID 54254043.
- S2CID 53172084.
- ^ Hews DK, Knapp R, Moore MC (1994). "Early exposure to androgens affects adult expression of alternative male types in tree lizards". Hormones and Behavior 28: 96-115.
- ^ ISSN 1365-2435.
- JSTOR 1565079.
- S2CID 51956358.
- JSTOR 2937254.
- ^ Herpedia: The Reptiles and Amphibians of Wyoming
- JSTOR 3892374.
- JSTOR 1565097.
- ^ JSTOR 1562825.
- JSTOR 1562825.
- JSTOR 3890577.
- JSTOR 3890577.
- ^ JSTOR 1562825.
- .
- ^ Weiss SL, Moore MC (2004). "Activation of aggressive behavior by progesterone and testosterone in male tree lizards, Urosaurus ornatus ". Gen. Comp. Endocrinol. 136 (2): 282–288.
- ^ M'Closkey RT, Baia KA, Russell RW (1987). "Tree lizard (Urosaurus ornatus) territories: experimental perturbation of the sex ratio". Ecology 68 (6): 2059-2062.
- ^ Zucker N, Boecklen W (1990). "Variation in female throat coloration in the tree lizard (Urosaurus ornatus): Relation to reproductive cycle and fecundity". Herpetologica 46 (4): 387-394.
- ^ Lattanzio M, Metro KJ, Miles DB (2014). "Preference for male traits differ in two female morphs of the tree lizard, Urosaurus ornatus ". PLoS ONE 9 (7): e101515. doi: 10.1371/journal.pone.0101515
- ^ ISBN 978-1-4214-0135-5. (Urosaurus ornatus schmidti, p. 236; U. o. schottii, p. 237; U. o. wrighti, p. 289).
Further reading
- Baird SF, Girard C (1852). "Characteristics of some New Reptiles in the Museum of the Smithsonian Institution. Second part". Proc. Acad. Nat. Sci. Philadelphia 6: 125-129. (Uta ornata, new species, p. 126).
- ISBN 0-394-50824-6. (Urosaurus ornatus, pp. 535–536 + Plate 369).
- Conant R (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. Boston: Houghton Mifflin Company. xviii + 429 pp. + Plates 1-48. (Urosaurus ornatus, pp. 108–109 + Plate 16 + Map 61).
- ISBN 978-0-544-12997-9. (Urosaurus ornatus, pp. 299–300 + Plate 28).
- ISBN 0-307-13666-3. (Urosaurus ornatus, pp. 112–113).
- ISBN 978-0-395-98272-3. (Urosaurus ornatus, pp. 296–297 + Plate 32 + Map 96).
- Zim HS, Smith HM (1956). Reptiles and Amphibians: A Guide to Familiar American Species: A Golden Nature Guide. New York: Simon and Schuster. 160 pp. (Urosaurus ornatus, pp. 54, 155).
External links
- Species Urosaurus ornatus at The Reptile Database