''Artemia parthenogenetica'' is a species of

brine shrimp ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia La ...

– aquatic

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s belonging to a different class, the Branchiopoda, than the true

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

Taxonomy

The name ''Artemia parthenogenetica'' is widely used in the relevant literature, although some taxonomists regard it as being used incorrectly to refer to parthenogenetic populations of ''Artemia'' that do not form a true species. A 2015 study based on

microsatellite A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. ...

markers showed that

parthenogenetic Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...

populations of different

ploidy Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of mat ...

levels group together in a

principal component analysis Principal component analysis (PCA) is a popular technique for analyzing large datasets containing a high number of dimensions/features per observation, increasing the interpretability of data while preserving the maximum amount of information, and ...

, and are distinct from related species such as ''

Artemia sinica ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia La ...

'', ''

Artemia tibetiana ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia La ...

'' and ''

Artemia urmiana ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia La ...

''.

Description

''A. parthenogenetica'' is an obligate parthenogenetic organism that is found in Europe, Africa, and Asia, from the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...

in the far west of its known range, east to Australia. It lives in hypersaline water bodies mostly along coastal waters of these continents. In Australia, scientists are debating whether the organism is native or introduced from birds. In inland Australia, genetic information indicates that populations have been introduced by migratory birds. As ''A. parthenogenetica'' can more favorably survive in high salinities, when large bodies of water dry out, the introductions of cysts by migrating birds from coastal regions may allow populations to become established, as happened in the

South Aral Sea The South Aral Sea was a lake in the basin of the former Aral Sea which formed in 1987 when that body divided in two, due to diversion of river inflow for agriculture. In 2003, the South Aral Sea itself split into eastern and western basins, th ...

in the late 1990s.

Life cycle

''A. parthenogenetica'', as its specific name suggests, is an obligate

organism, one that reproduces without sexual reproduction. Like other brine shrimp, ''A. parthenogenetica'' produces cysts that are highly resistant to environmental changes, including large changes in temperature and salinity, and the stress of drying out and exposure to UV radiation. The organism displays different numbers of chromosomes or levels of

, from diploid to 5n. ''A. parthenogenetica'' populations with 2n ploidy have some recombination of genes during

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately resu ...

then fuse the recombined cells to regain the 2n chromosomes. In populations with ploidies from 3n to 5n, the resultant offspring are

clones Clone or Clones or Cloning or Cloned or The Clone may refer to: Places * Clones, County Fermanagh * Clones, County Monaghan, a town in Ireland Biology * Clone (B-cell), a lymphocyte clone, the massive presence of which may indicate a pathologi ...

of the parents.

Automixis

Diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

''A. parthenogenetica'' can undergo

, but instead of producing haploid

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...

s as ordinarily occurs in sexual species, diploid meiotic products are most often produced by

automixis ''Automixis'' is the fusion of (typically haploid) nuclei or gametes derived from the same individual. The term covers several reproductive mechanisms, some of which are parthenogenetic. Diploidy might be restored by the doubling of the chromoso ...

.Boyer L, Jabbour-Zahab R, Mosna M, Haag CR, Lenormand T. Not so clonal asexuals: Unraveling the secret sex life of Artemia parthenogenetica. Evol Lett. 2021 Feb 8;5(2):164-174. doi: 10.1002/evl3.216. PMID: 33868712; PMCID: PMC8045904 Automixis involves the fusion of nuclei derived from the same individual meiosis. The specific type of automixis occurring in ''A. partheogenetica'' is likely “central fusion”, that is fusion of the first two meiotic products (see Figure in

Automixis ''Automixis'' is the fusion of (typically haploid) nuclei or gametes derived from the same individual. The term covers several reproductive mechanisms, some of which are parthenogenetic. Diploidy might be restored by the doubling of the chromoso ...

). Automixis allows ''A. parthenogenetica'' to reproduce parthenogenetically. However, despite its species designation as “''parthenogentica''” implying obligate parthenogenesis, recent evidence indicates that this species is also capable of infrequently reproducing sexually.

References

{{Taxonbar, from=Q4553244 Anostraca Crustaceans described in 1978