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''Sceloporus virgatus'', commonly known as the striped plateau lizard, is a species of lizard within the genus '' Sceloporus''. This genus is known for the signaling modalities that it uses and exhibits, including visual motion and chemical signals that aid in identifying their territories as well as color that indicates aggression. The striped plateau lizard originates from the northern
Sierra Madre Occidental The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through northwestern and western Mexico, and along the Gulf of California. The Sierra Madre is part of the American C ...
and is relatively small in size, measuring less than in length.


Etymology

"Virgatus" is a Latin word, and it signifies "of twigs" and "rodlike". This term represents the distinct, light line with a dark band below it on the dorsal surface of the striped plateau lizard.


Description


Physical body

''Sceloporus virgatus'' has an average body mass of and an average body length of . The striped plateau lizard has a pair of whiteish-yellow stripes on the dorsolateral sides of its body. Hence, the lizard gets its common name from its physical description of stripes, creating the "striped plateau lizard". In females, these stripes tend to appear more as a pale brown. Between the stripes, the body of the striped plateau lizard is colored gray, brown, or tan. This area is also delineated by two vertical rows of lightly shaded spots with dark edges. These spots are slightly difficult to see as they often appear faint and mostly dark in color without white spots in the center. There is another lightly shaded, lateral stripe located low on each side of the lizard, going from the neck to the groin area. The area between the dorsolateral and lateral stripes also tends to be darker than the mid-dorsal area of the body. The ventral underside of the striped plateau lizard, particularly the belly area, is a solid cream in color, with no pattern. However, near the throat, there is a small, faint green or pale blue spot ventrally on the adult lizards. These animals are
sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
and there are many differences between males and females. For instance, the colored spots on the throat become bordered with orange or the orange color replaces any faint green or pale blue coloration in reproductive females. The chests of the striped plateau lizards also have a few black spots. Moreover, scales run in rows on the dorsal side of the bodies, in particular, diagonally, upward, and back to the rear side. The lizards also have pores, and for the scales that are located where the pores are, they are notched posteriorly. These scales and pores are most noticeable in male striped plateau lizards. Males are also smaller in size than females, measuring to less than in length. In addition, they have enlarged post-anal scales and swollen tail bases. In comparison to the female striped plateau lizards, the dorsal spotting on males tends to be less distinct, but the striping, the throat patches, and the body color are more vivid and clear.


Visual and hearing systems

As part of its visual system, the striped plateau lizard has corneal eyes. A curved
cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
is an image-forming lens due to the difference in
refractive indices In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...
between air and corneal tissue. In land vertebrates, many species with corneal eyes also have lenses, but for these species, the lenses are flatter and weaker than those of aquatic species. However, corneal eyes cannot focus in aquatic habitats. Thus, the cornea is the source of most of the refractive power for land vertebrates. As for the auditory system of the striped plateau lizard, this species has a tympanic middle ear. This is a cavity between the outer ear and the inner ear, and it is filled with air. When auditory vibrations hit the
tympanic membrane In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air ...
, or ear drum, sound is processed and heard.


Habitat and distribution

The striped plateau lizard is primarily a terrestrial and
montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...
species since they reside on land, particularly in the temperate forest and in the moist savanna. ''S. virgatus'' is most abundantly found in mixed pine and oak woods or in wooded canyons and ravines. It ranges upward into pine forests and downward in oak woodlands located along streams. As the images to the right depict, the striped plateau lizard tends to favor hard and rough surfaces on the ground like rocks, leaf litter, logs, and scattered grasses. They can also be found near sandy, rocky intermittent streams. ''Sceloporus virgatus'' is widely found in
Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, Ne ...
in the geographical range between extreme southeastern
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
and extreme southwestern
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...
, including
Chiricahua Chiricahua ( ) is a band of Apache Native Americans. Based in the Southern Plains and Southwestern United States, the Chiricahua (Tsokanende ) are related to other Apache groups: Ndendahe (Mogollon, Carrizaleño), Tchihende (Mimbreño), Sehende ...
, Peloncillo, Guadalupe, and
Animas mountains The Animas Mountains are a small mountain range in Hidalgo County, within the " Boot-Heel" region of far southwestern New Mexico, in the United States. They extend north–south for about 30 miles (50 km) along the Continental Divide,Since ...
. This geographical range also extends south to the Sierra Madre Occidental and to southern Chihuahua in Mexico. With the striped plateau lizard being a montane population, it is isolated geographically by the semi-desert grassland and by the desert-scrub valleys, which are now inhospitable for many other species. More than ten thousand years ago, the desert-scrub valleys were a lot cooler and the woodlands extended down into the valleys, forming a continuous, rather than segregated, habitat for ''S. virgatus''. However, due to the changes in climate and the changes in habitat surroundings, the striped plateau lizard species has become relatively isolated for a very long time.


Reproduction

The striped plateau lizard sexually reproduces and are
oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...
animals, indicating that the striped plateau lizard lays eggs and that their offspring hatch from the eggs after coming out of the mothers' bodies. The brood size is 0.291, and the striped plateau lizard produces around one litter per year. When females mature at around in body length, they typically lay a clutch consisting between three and eighteen eggs. This laying of eggs occurs at the beginning of the summer rainy season, which takes place from late June until late July. The size of the clutches are associated with the precipitation and temperature over the past year. Then, hatchlings appear in late August and September, being around in body length. The population of ''S. virgatus'' is currently stable at around 100,000 individuals, though it is severely fragmented as the number of mature individuals present is continuing to decline. This can lead to an over-abundance of younger striped plateau lizards in the population, which can contribute to slower population growth in the future and be detrimental to the presence of the species as a whole.


Behavior

The striped plateau lizard are diurnal as they are active during the daytime and sleep and remain inactive during the nighttime. This species of lizard seeks shelter and are inactive in cold temperatures and extreme heat.


Social interactions

Differences between sexes exist when interacting within the species and outside of the species. While both male and female striped plateau lizards defend territories against other individuals of their same sex, the interactions between males tend to be more aggressive. On the other hand, interactions between males and females are ruled by courtship.


Signaling modalities

Signals are vital to communicating and conveying information well, and ''Sceloporus'' lizards combine visual and chemical displays to defend territories and attract mates. In ''S. virgatus'' specifically, loss of the color signal is correlated with an increase in chemical behavior but no change in the use of the motion display. Male striped plateau lizards, for instance, use both visual motion with head-bobs, and they use chemical signals to identify their territory and its boundaries. The males use color, specifically the blue patches of color on their bellies, to indicate aggression. This belly color also seems to get more attention from males than from females, which makes sense with the context that it is used in. In particular, as there were more evolutionary changes in the visual motion of head-bobs, there were fewer chemical signals of the large femoral pores associated with the evolutionary changes. The three signals of motion, color, and chemical cues have evolved differently over time. Firstly, head-bob displays have evolved relatively quickly in response to different selective pressures. For example, arboreality, or the tendency to live in trees, has been shown to affect the evolution of head-bob signals as ''Sceloporus'' living in trees seem to produce less jagged head-bob displays than ''Sceloporus'' living terrestrially, on land. Thus, lizards that use more head-bobs are also more likely to have evolved an arboreal lifestyle, as well as viviparity. Secondly, the loss of blue belly patches correlates with a lower chance that lizards have evolved
arboreality Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose num ...
or
viviparity Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...
. Thirdly, chemical cues are only really associated with arboreality, as arboreal lizards are more likely to have fewer femoral pores.


Predator and prey

The locomotion of the striped plateau lizard involves running and climbing. ''Sceloporus virgatus'' are invertivores in the sense that they eat insects and other
arthropods Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
. Their preferred method of catching prey is via a sudden ambush technique. As these lizards are rather sedentary, this is also called a sit-and-wait method, in which ''S. virgatus'' sits and waits for a prey to come up and then ambushes the prey.


Conservation

The striped plateau lizard is present in some regions that are protected. Yet, no direct conservation actions are needed for this particular species. Fortunately, as per the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
, ''S. virgatus'' is listed as "least concern". Something to watch out for is their isolation pockets, as it might pose a threat to genetic diversity in the population.


References

{{Taxonbar, from=Q4745696 Sceloporus Fauna of the Sierra Madre Occidental Endemic reptiles of Mexico Reptiles described in 1938 Taxa named by Hobart Muir Smith