Desert grassland whiptail lizard | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Family: | Teiidae |
Genus: | Aspidoscelis |
Species: | A. uniparens |
Binomial name | |
Aspidoscelis uniparens (Wright & Lowe, 1965) | |
Synonyms | |
Cnemidophorus uniparensWright & Lowe, 1965 |
The desert grassland whiptail lizard (Aspidoscelis uniparens) is an all-female species of reptiles in North America. It was formerly placed in the genus Cnemidophorus . A common predator of the whiptail lizard is the leopard lizard that preys on A. uniparens by using ambush and stalk hunting tactics. [2] [3] [4] These reptiles reproduce by parthenogenesis. In this process, eggs undergo a chromosome doubling after meiosis, developing into lizards without being fertilized. However, ovulation is enhanced by female-female courtship and mating (pseudo-copulation) rituals that resemble the behavior of closely related species that reproduce sexually. [5] [6] [7]
The desert grassland whiptail lizard is a relatively small reptile, whose size ranges from 2+3⁄4 to 5+1⁄4 inches (7.0 to 13.3 cm). [8] Desert grassland whiptails are very long and slim, with a thin tail that is longer than their body length. Their distinct identifying feature are the six yellowish lines that run the length of their body. The majority of the whiptail's body tends to be an olive or brown colour that fades to a faint blue or gray on their tail. Comparatively, an adolescent's tail is a very bright and vibrant blue. [9] Their bodies are lined with small coarse scales, which gradually get larger as they approach the tail. The scales on their bellies are much larger in size and are much smoother as well.
The taxonomy of the genus was unknown until the 1950s to early '60's. A 1958 report confirmed that no male lizards had been discovered in a collection of specimens of C. tesselatus. That very year, parthenogenesis was confirmed in the genus Lacerta of the family Lacertidae. Soon after, researchers discovered that there were also no males in C. exsanguis, C. neomexicanus, or C. velox. [10] Rather than subsume all cnemidophorine species into a single large genus, Lowe and Wright proposed a split that placed the North American "Cnemidophorus" clade in the monophyletic genus Aspidoscelis. Under this arrangement, South American taxa remain in the genus Cnemidophorus. [1]
The desert grassland whiptail is mostly found in the deserts of southern to central Arizona and along the Rio Grande river in New Mexico. It is also found in the deserts of northern Mexico. A. uniparens is commonly found in low valleys, grasslands, and slight slopes. Some have argued that the species' range is expanding due to overgrazing. A. uniparens are scarce in developed areas, especially where homeowners keep livestock. [11]
All desert grassland whiptail lizards are female. Their reproduction process does not need male fertilization, although researchers observed pseudo-copulation that promotes fertilization during ovulation. This process involves the alternation between male-typical and female-typical sexual behaviours, driven by progesterone, in both lizards; corresponding to the state of their partner. [12] The lizards reproduce by parthenogenesis and are clones of their mother. Under normal reproductive processes, a species has each chromosome pair separated, copied, and paired back with its counterpart. The desert grassland whiptail lizard, however, has chromosome triplets where each triplet is paired with its copy rather than its counterparts. This reproductive method enables the asexual desert grassland whiptail lizard to have a genetic diversity previously thought to have been unique to sexually reproductive species. [13]
The lizards were a result from a cross breed of two bisexual species, A. inornata and A. burti. This then produced a diploid unisexual, which backcrossed to inornata and produced triploid uniparens. [14]
For the most part, the Desert grassland whiptail digs for termites, Queen ants, beetles, and unidentified insects. [15] A smaller portion of their diet includes prey found above ground such as grasshoppers and butterflies.
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited. Komodo dragons and some monitor lizards can reproduce asexually.
Teiidae is a family of Lacertoidean lizards native to the Americas. Members of this family are generally known as whiptails or racerunners; however, tegus also belong to this family. Teiidae is sister to the Gymnopthalmidae, and both families comprise the Teiioidea. The Teiidae includes several parthenogenic species – a mode of clonal reproduction. Presently, the Teiidae consists of approximately 150 species in eighteen genera.
Cnemidophorus is a genus of lizards in the family Teiidae. Species in the genus Cnemidophorus are commonly referred to as whiptail lizards or racerunners. The genus is endemic to South America, Central America, and the West Indies.
Aspidoscelis is a genus of whiptail lizards in the family Teiidae.
The western whiptail is a species of lizard in the family Teiidae. The species is found throughout most of the southwestern United States and northern Mexico. Most of its populations appear stable, and it is not listed as endangered in any of the states comprising its range. It lives in a wide variety of habitats, including deserts and semiarid shrubland, usually in areas with sparse vegetation; it also may be found in woodland, open dry forest, and riparian growth. It lives in burrows. Major differences between this species and the checkered whiptail include the lack of enlarged scales anterior to the gular fold and the presence of enlarged postantebrachial scales. It was previously known as Cnemidophorus tigris, until phylogenetic analyses concluded that the genus Cnemidophorus was polyphyletic. Since it does not migrate, a number of forms have developed in different regions, several of which have been given subspecific names – for example the California whiptail, Aspidoscelis tigris munda.
Thelytoky is a type of parthenogenesis and is the absence of mating and subsequent production of all female diploid offspring as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in about 1,500 species, about 1 in 1000 of described animal species, according to a 1984 study. It is more common in invertebrates, like arthropods, but it can occur in vertebrates, including salamanders, fish, and reptiles such as some whiptail lizards.
The Texas spotted whiptail is a species of long-tailed lizard, in the family Teiidae. The species is endemic to the south central and southwestern United States and northern Mexico. Six subspecies are recognized as being valid.
The gray checkered whiptail, also known commonly as Dixon's whiptail and the gray-checkered whiptail, is a species of lizard in the family Teiidae. The species is native to northern Mexico, and to the United States in southern New Mexico and western Texas.
The Chihuahuan spotted whiptail is a species of lizard native to the United States in southern Arizona, southern New Mexico and southwestern Texas, and northern Mexico in northern Chihuahua and northern Sonora.
The Laredo striped whiptail is a species of lizard found in the southern United States, in Texas, and northern Mexico in Coahuila, Nuevo Leon, and Tamaulipas. Some sources believe it to be the result of extensive hybridization between the Texas spotted whiptail, Aspidoscelis gularis and the six-lined racerunner, Aspidoscelis sexlineatus. It is one of many lizard species known to be parthenogenic.
The marbled whiptail is a species of lizard found in the United States, in southern New Mexico and Texas, and in northern Mexico, in Coahuila, Chihuahua and Durango.
The New Mexico whiptail is a female-only species of lizard found in New Mexico and Arizona in the southwestern United States, and in Chihuahua in northern Mexico. It is the official state reptile of New Mexico. It is one of many lizard species known to be parthenogenetic. Individuals of the species can be created either through the hybridization of the little striped whiptail and the western whiptail, or through the parthenogenetic reproduction of an adult New Mexico whiptail.
The plateau spotted whiptail is a species of lizard found in the southern United States in Texas, and in northern Mexico in Chihuahua and Coahuila. It is known to hybridize with the Eastern Spotted Whiptail, Cnemidophorus gularis, but is considered to be a distinct species due to phenotypic characteristics.
The six-lined racerunner is a species of lizard native to the United States and Mexico.
The little striped whiptail is a species of lizard found in the southwestern United States and in northern Mexico. A significant amount of research was done on the species during the mid-1990s, with several new subspecies being added, many of which some sources consider to be distinct enough to warrant full species status, and the research is ongoing. It is called little to distinguish it from many other species known as striped whiptails and to indicate that it is the smallest of those species.
Parthenogenesis is a natural form of asexual reproduction in which growth and development of an embryo occur directly from an egg, without need for fertilization. In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg.
Parthenogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. Among all the sexual vertebrates, the only examples of true parthenogenesis, in which all-female populations reproduce without the involvement of males, are found in squamate reptiles. There are about 50 species of lizard and 1 species of snake that reproduce solely through parthenogenesis. It is unknown how many sexually reproducing species are also capable of parthenogenesis in the absence of males, but recent research has revealed that this ability is widespread among squamates.
Aspidoscelis costatus, also known as the western Mexico whiptail, is a species of whiptail lizard endemic to Mexico, including Guerrero, Morelos, and Puebla in southern Mexico, as well as other Mexican states. Its range spans both temperate and tropical habitats, and even densely populated urban areas. Its common name, the Western Mexico Whiptail, can easily be confused with the Western Whiptail, which refers to a different lizard, Aspidoscelis tigris.
Aspidoscelis rodecki, also known commonly as Rodeck's whiptail, is a species of lizard in the family Teiidae. The species is endemic to Mexico.
Lutes, A. A., Neaves, W.B., Baumann, D. P., Wiegraebe, W., Baumann, P. (2010). Sister chromosome pairing maintains heterozygosity in parthenogenetic lizards. nature.com. Web 22 Oct. 2014.
Mayer, Greg. (2010). Hybridization and Parthenogenesis in Whiptail Lizards. whyevolutionistrue.wordpress.com. Web 23 Oct 2014.
Harmon Katherine (2010) No Sex Needed: All-Female Lizard Species Cross Their Chromosomes to Make Babies. www.scientificamerican.com/article/asexual-lizards/ Tue 21 Oct 2014.
S. C. Woolley, J. T. Sakata D. Crews(2004) Tracing the Evolution of Brain and Behavior Using Two Related Species of Whiptail Lizards: Cnemidophorus uniparens and Cnemidophorus inornatus ilarjournal.oxfordjournals.org/content/45/1/46.full Tue 21 Oct 2014.
Maryanne E. Tocidlowski, Christine L. Merrill, Michael R. Loomis, and James F. Wright 2001 TERATOMA IN DESERT GRASSLAND WHIPTAIL LIZARDS (CNEMIDOPHORUS UNIPARENS). www.bioone.org/doi/pdf/10.1638/1042-7260(2001)032%5B0257:TIDGWL%5D2.0.CO%3B2 Tue 21 Oct 2014