The Arizona striped whiptail (''Aspidoscelis arizonae'') is a species of whiptail lizard endemic to the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. This is a species of lizards that lives in

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

's grassy desert areas and is normally found hiding in desert shrubs. They are approximately long, and, like all whiptails, they have a noticeably long whiplike tail hence the name whiptail and they are fast runners . ''A. arizonae'' are identifiable by their brown and blue bodies with noticeable yellow stripes. They are easily confused with the Pai striped whiptail.

Facultative parthenogenesis

''A. arizonae'' haploid unfertilized

oocyte An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ger ...

s can undergo facultative

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

by a post-meiotic mechanism resulting in

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

wide homo

zygosity Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mos ...

. In many species that are capable of facultative parthenogenesis, the transition to the completely homozygous condition leads to exposure of the

genetic load Genetic load is the difference between the fitness of an average genotype in a population and the fitness of some reference genotype, which may be either the best present in a population, or may be the theoretically optimal genotype. The average ...

and results in embryonic mortality and an elevated rate of

congenital malformations A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

. Despite this risk, in ''A. arizonae'' a small percentage of unfertilized oocytes are able to undergo parthenogenesis and develop normally. Thus, in the case of ''A. arizonae'', facultative parthenogenesis can potentially allow

purifying selection In natural selection, negative selection or purifying selection is the selective removal of alleles that are deleterious. This can result in stabilising selection through the purging of deleterious genetic polymorphisms that arise through random ...

to happen with the consequence that all lethal recessive

allele An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule. Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), ...

s are purged in just one generation.

References

Reptiles described in 1896 Aspidoscelis Taxa named by John Van Denburgh {{Arizona-stub