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[[File:Cnemidophorus-ThreeSpecies.jpg|thumb|280px|right|The asexual, all-female whiptail species ''[[Cnemidophorus neomexicanus]]'' (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males ''[[Cnemidophorus inornatus|C. inornatus]]'' (left) and ''[[Cnemidophorus tigris|C. tigris]]'' (right), which hybridized naturally to form the ''C. neomexicanus'' species.]]
[[File:Cnemidophorus-ThreeSpecies.jpg|thumb|280px|right|The asexual, all-female whiptail species ''[[Cnemidophorus neomexicanus]]'' (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males ''[[Cnemidophorus inornatus|C. inornatus]]'' (left) and ''[[Cnemidophorus tigris|C. tigris]]'' (right), which hybridized naturally to form the ''C. neomexicanus'' species.]]


'''Parthenogenesis Is A Very Very Very Very Sick method Ever. And also A good Friend Of Mariyam Agha'''
'''Parthenogenesis''' ({{IPAc-en|ˌ|p|ɑːr|θ|ᵻ|n|oʊ|ˈ|dʒ|ɛ|n|ᵻ|s|ᵻ|s|,_|-|θ|ᵻ|n|ə|-}};{{refn|{{MerriamWebsterDictionary|parthenogenesis}}}}{{refn|{{cite web |url=https://www.oxforddictionaries.com/definition/english/parthenogenesis |title=parthenogenesis - definition of parthenogenesis in English from the Oxford dictionary |publisher=[[OxfordDictionaries.com]] |access-date=2016-01-20 }}}} from the Greek παρθένος parthenos, "virgin", + γένεσις genesis, "creation"<ref>Liddell, Scott, Jones. [http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0057:entry%3Dge/nesis γένεσις] A.II, ''A Greek-English Lexicon'', Oxford: Clarendon Press, 1940. ''q.v.''.</ref>) is a natural form of [[asexual reproduction]] in which growth and development of [[embryos]] occur without [[fertilization]]. In [[animal]]s, parthenogenesis means development of an embryo from an unfertilized [[Gametophyte|egg cell]]. In [[plant]]s parthenogenesis is a component process of [[apomixis]].


m
Gynogenesis and [[pseudogamy]] are closely related phenomena in which a [[sperm]] or [[pollen]] triggers the development of the egg cell into an [[embryo]] but makes no genetic contribution to the embryo. The rest of the [[Cell biology|cytology]] and [[genetics]] of these phenomena are mostly identical to that of parthenogenesis.

The term is sometimes used inaccurately to describe reproduction modes in [[hermaphrodite|hermaphroditic]] species that can reproduce by themselves because they contain reproductive organs of both sexes in a single individual's body. However, these species still use fertilization.

Parthenogenesis occurs naturally in many plants, some [[invertebrate]] animal species (including [[nematodes]], [[water flea]]s, some [[scorpion]]s, [[aphid]]s, some mites, some [[bee]]s, some [[Phasmida]] and [[parasitic wasp]]s) and a few [[vertebrate]]s (such as some [[fish]],<ref>[http://www.washingtonpost.com/wp-dyn/content/article/2007/05/22/AR2007052201405.html "Female Sharks Can Reproduce Alone, Researchers Find"], Washington Post, Wednesday, May 23, 2007; Page A02</ref> [[amphibians]], [[reptile]]s<ref name="reptiles">{{cite book| last = Halliday| first = Tim R.| editor = Kraig Adler | title = Reptiles & Amphibians| publisher = Torstar Books| year= 1986| page = 101| isbn = 0-920269-81-8 }}</ref><ref>{{cite news| title = Scientists discover unknown lizard species at lunch buffet| first = Brian| last = Walker| url = http://www.cnn.com/2010/LIVING/11/10/lizard.lunch.discovery/| newspaper = CNN| accessdate = 2010-11-11| date=2010-11-11}}</ref> and very rarely [[bird]]s<ref>{{cite web|last = Savage| first = Thomas F.| title = A Guide to the Recognition of Parthenogenesis in Incubated Turkey Eggs| work = Oregon State University| date= September 12, 2005| url=http://oregonstate.edu/instruct/ans-tparth/index.html| accessdate = 2006-10-11 }}</ref>). This type of reproduction has been induced artificially in a few species including fish and amphibians.<ref name=Booth />

Normal egg cells form after [[meiosis]] and are [[haploid]], with half as many chromosomes as their mother's body cells. Haploid individuals, however, are usually non-viable, and parthenogenetic offspring usually have the [[diploid]] chromosome number. Depending on the mechanism involved in restoring the diploid number of chromosomes, parthenogenetic offspring may have anywhere between all and half of the mother's [[allele]]s. The offspring having all of the mother's genetic material are called full [[Cloning|clones]] and those having only half are called half clones. Full clones are usually formed without meiosis. If meiosis occurs, the offspring will get only a fraction of the mother's alleles.

Parthenogenetic offspring in species that use either the [[XY sex-determination system|XY]] or the [[X0 sex-determination system|X0]] sex-determination system have two X chromosomes and are female. In species that use the [[ZW sex-determination system]], they have either two Z chromosomes (male) or two W chromosomes (mostly non-viable but rarely a female), or they could have one Z and one W chromosome (female).

== Life history types ==
Some species reproduce exclusively by parthenogenesis (such as the [[Bdelloidea|Bdelloid rotifers]]), while others can switch between sexual reproduction and parthenogenesis. This is called facultative parthenogenesis (other terms are cyclical parthenogenesis, heterogamy<ref>{{cite book| publisher = Walter de Gruyter| isbn = 978-3-11-010661-9| last = Scott| first = Thomas| title = Concise encyclopedia biology| year = 1996}}</ref><ref>{{cite journal| issn = 0165-5752 | volume = 52| issue = 3| pages = 219–225| last = Poinar| first = George O, Jr |author2=Trevor A Jackson |author3=Nigel L Bell |author4=Mohd B-asri Wahid| title = Elaeolenchus parthenonema n. g., n. sp. (Nematoda: Sphaerularioidea: Anandranematidae n. fam.) parasitic in the palm-pollinating weevil Elaeidobius kamerunicus Faust, with a phylogenetic synopsis of the Sphaerularioidea Lubbock, 1861| journal = Systematic Parasitology| date = July 2002| pmid=12075153| doi = 10.1023/A:1015741820235}}</ref> or heterogony<ref name=White1984>{{cite journal| doi = 10.1080/11250008409439455| issn = 0373-4137| volume = 51| issue = 1–2| pages = 1–23| last = White| first = Michael J.D.| title = Chromosomal Mechanisms in Animal Reproduction| journal = Bolletino di zoologia| year = 1984}}</ref><ref name=Pujade-Villar2001>{{cite journal| volume = 11| issue = 1999| pages = 87–107| last = Pujade-Villar| first = Juli|author2=D. Bellido |author3=G. Segu |author4=George Melika | title = Current state of knowledge of heterogony in Cynipidae (Hymenoptera, Cynipoidea)| journal = Sessio Conjunta dEntomologia ICHNSCL| year = 2001}}</ref>). The switch between sexuality and parthenogenesis in such species may be triggered by the season ([[aphid]], some [[gall wasps]]), or by a lack of males or by conditions that favour rapid population growth ([[rotifers]] and [[cladocerans]] like [[daphnia]]). In these species asexual reproduction occurs either in summer (aphids) or as long as conditions are favourable. This is because in asexual reproduction a successful genotype can spread quickly without being modified by sex or wasting resources on male offspring who won't give birth. In times of stress, offspring produced by sexual reproduction may be fitter as they have new, possibly beneficial gene combinations. In addition, sexual reproduction provides the benefit of meiotic recombination between non-sister chromosomes, a process associated with repair of DNA double-strand breaks and other DNA damages that may be induced by stressful conditions.<ref>{{cite journal | last1 = Bernstein | first1 = H | last2 = Hopf | first2 = FA | last3 = Michod | first3 = RE | year = 1987 | title = The molecular basis of the evolution of sex | url = | journal = Adv Genet | volume = 24 | issue = | pages = 323–370 | doi = 10.1016/s0065-2660(08)60012-7 | pmid = 3324702 | series = Advances in Genetics | isbn = 978-0-12-017624-3 }}</ref><ref>Harris Bernstein, Carol Bernstein and Richard E. Michod (2011). Meiosis as an Evolutionary Adaptation for DNA Repair. Chapter 19 in DNA Repair. Inna Kruman editor. InTech Open Publisher. DOI: 10.5772/25117 http://www.intechopen.com/books/dna-repair/meiosis-as-an-evolutionary-adaptation-for-dna-repair</ref> (See also [[Meiosis]] section: Origin and function of meiosis.)

Many taxa with heterogony have within them species that have lost the sexual phase and are now completely asexual. Many other cases of obligate parthenogenesis (or gynogenesis) are found among polyploids and hybrids where the chromosomes cannot pair for meiosis.

The production of female offspring by parthenogenesis is referred to as [[thelytoky]] (e.g., aphids) while the production of males by parthenogenesis is referred to as [[arrhenotoky]] (e.g., bees). When unfertilized eggs develop into both males and females, the phenomenon is called deuterotoky.<ref name=Gavrilov2007>{{cite journal| last1= Gavrilov | first1 = I.A. | last2 = Kuznetsova | first2 = V.G. | title =On some terms used in the cytogenetics and reproductive biology of scale insects (Homoptera: Coccinea) |journal = Comparative Cytogenetics | year = 2007 | volume = 1 | issue= 2 |pages = 169–174 | issn = 1993-078X | url=http://www.zin.ru/Journals/compcyt/pdf/1/GavrilovKuznetsova.pdf}}</ref>

== Types and mechanisms ==
Parthenogenesis can occur without meiosis through mitotic oogenesis. This is called '''apomictic parthenogenesis'''. Mature egg cells are produced by mitotic divisions, and these cells directly develop into embryos. In flowering plants, cells of the [[gametophyte]] can undergo this process. The offspring produced by apomictic parthenogenesis are ''full clones'' of their mother. Examples include aphids.

Parthenogenesis involving [[meiosis]] is more complicated. In some cases, the offspring are haploid (e.g., male [[ants]]). In other cases, collectively called '''automictic parthenogenesis''', the ploidy is restored to diploidy by various means. This is because haploid individuals are not viable in most species. In automictic parthenogenesis the offspring differ from one another and from their mother. They are called ''half clones'' of their mother.

=== Automictic parthenogenesis ===
[[File:Central fusion and terminal fusion automixis.svg|thumb|280px|right|The effects of central fusion and terminal fusion on heterozygosity]]
''Automixis'' is a term that covers several reproductive mechanisms, some of which are parthenogenetic.<ref name=Mogie>{{cite journal |last1=Mogie |first1=Michael |title=Automixis: its distribution and status |journal=Biological Journal of the Linnean Society |volume=28 |pages=321–9 |year=1986 |doi=10.1111/j.1095-8312.1986.tb01761.x |issue=3}}</ref>

Diploidy might be restored by the doubling of the chromosomes without cell division before meiosis begins or after meiosis is completed. This is referred to as an ''[[Endoreduplication|endomitotic]]'' cycle. This may also happen by the fusion of the first two [[blastomeres]]. Other species restore their ploidy by the fusion of the meiotic products. The chromosomes may not separate at one of the two anaphases (called '''restitutional meiosis'''), or the nuclei produced may fuse or one of the polar bodies may fuse with the egg cell at some stage during its maturation.

Some authors consider all forms of automixis sexual as they involve recombination. Many others classify the endomitotic variants as asexual, and consider the resulting embryos parthenogenetic. Among these authors the threshold for classifying automixis as a sexual process depends on when the products of anaphase I or of anaphase II are joined together. The criterion for "sexuality" varies from all cases of restitutional meiosis,<ref name=Zakharov2005>{{cite journal | doi = 10.1007/s11177-005-0103-z| issn = 1022-7954 | volume = 41| issue = 4| pages = 402–411| last = Zakharov| first = I. A.| title = Intratetrad mating and its genetic and evolutionary consequences| journal = Russian Journal of Genetics| accessdate = 2011-12-19| date = April 2005| url = http://www.springerlink.com/content/q7u8516471xn5518/}}</ref> to those where the nuclei fuse or to only those where gametes are mature at the time of fusion.<ref name=Mogie /> Those cases of automixis that are classified as sexual reproduction are compared to [[self-fertilization]] in their mechanism and consequences.

The genetic composition of the offspring depends on what type of apomixis takes place. When endomitosis occurs before meiosis<ref name=Cosin2011>Cosín, Darío J. Díaz, Marta Novo, and Rosa Fernández. "Reproduction of Earthworms: Sexual Selection and Parthenogenesis." In Biology of Earthworms, edited by Ayten Karaca, 24:69–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://www.springerlink.com/content/j5j72p2834355w27/.</ref><ref name=Cuellar1971>{{cite journal| doi = 10.1002/jmor.1051330203| issn = 1097-4687| volume = 133| issue = 2| pages = 139–165| last = Cuellar| first = Orlando| title = Reproduction and the mechanism of meiotic restitution in the parthenogenetic lizard Cnemidophorus uniparens| journal = Journal of Morphology| date = 1971-02-01| pmid = 5542237}}</ref> or when ''central fusion'' occurs (restitutional meiosis of anaphase I or the fusion of its products), the offspring get all<ref name=Cosin2011 /><ref name=Lokki1975>{{cite journal| volume = 79| issue = 3| pages = 513–525| last = Lokki| first = Juhani|author2=Esko Suomalainen |author3=Anssi Saura |author4=Pekka Lankinen | title = Genetic Polymorphism and Evolution in Parthenogenetic Animals. Ii. Diploid and Polyploid Solenobia Triquetrella (lepidoptera: Psychidae)| journal = Genetics| accessdate = 2011-12-20| date = 1975-03-01| url =http://www.genetics.org/content/79/3/513.abstract| pmid = 1126629| pmc = 1213290}}</ref> to more than half of the mother's genetic material and heterozygosity is mostly preserved<ref name=Groot2003>{{cite journal| issn = 0018-067X| volume = 90| issue = 2| pages = 130–135| last = Groot| first = T V M|author2=E Bruins |author3=J A J Breeuwer | title = Molecular genetic evidence for parthenogenesis in the Burmese python, ''Python molars bivittatus''| journal = Heredity| date = 2003-02-28|format=Free full text| doi=10.1038/sj.hdy.6800210| pmid = 12634818}}</ref> (if the mother has two alleles for a locus, it is likely that the offspring will get both). This is because in [[anaphase I]] the homologous chromosomes are separated. Heterozygosity is not completely preserved when crossing over occurs in central fusion.<ref name=Pearcy2004>{{cite journal |last1=Pearcy |first1=M. |last2=Aron |first2=S |last3=Doums |first3=C |last4=Keller |first4=L |title=Conditional Use of Sex and Parthenogenesis for Worker and Queen Production in Ants |journal=Science |volume=306 |issue=5702 |pages=1780–3 |year=2004 |pmid=15576621 |doi=10.1126/science.1105453}}</ref> In the case of pre-meiotic doubling, recombination -if it happens- occurs between identical sister chromatids.<ref name=Cosin2011 />

If ''terminal fusion'' (restitutional meiosis of anaphase II or the fusion of its products) occurs, a little over half the mother's genetic material is present in the offspring and the offspring are mostly homozygous.<ref name=Booth2011>{{cite journal| doi = 10.1093/jhered/esr080| volume = 102| issue = 6| pages = 759–763| last = Booth| first = Warren|author2=Larry Million |author3=R. Graham Reynolds |author4=Gordon M. Burghardt |author5=Edward L. Vargo |author6=Coby Schal |author7=Athanasia C. Tzika |author8=Gordon W. Schuett | title = Consecutive Virgin Births in the New World Boid Snake, the Colombian Rainbow Boa, ''Epicrates maurus''| journal = Journal of Heredity| accessdate = 2011-12-17| date = December 2011| url = http://jhered.oxfordjournals.org/content/102/6/759.abstract| pmid = 21868391}}</ref> This is because at anaphase II the [[sister chromatids]] are separated and whatever heterozygosity is present is due to crossing over. In the case of endomitosis after meiosis the offspring is completely homozygous and has only half the mother's genetic material.

This can result in parthenogenetic offspring being unique from each other and from their mother.

=== Sex of the offspring ===
In apomictic parthenogenesis, the offspring are clones of the mother and hence are usually (except for [[aphid]]s) female. In the case of aphids, parthenogenetically produced males and females are clones of their mother except that the males lack one of the X chromosomes (XO).<ref name=Hales2002>{{cite journal| doi = 10.1017/S0016672302005657| volume = 79| issue = 3| pages = 203–209| last = Hales| first = Dinah F. |author2=Alex C. C. Wilson |author3=Mathew A. Sloane |author4=Jean-Christophe Simon |author5=Jean-François Legallic |author6=Paul Sunnucks| title = Lack of Detectable Genetic Recombination on the X Chromosome During the Parthenogenetic Production of Female and Male Aphids| journal = Genetics Research| year = 2002}}</ref>

When meiosis is involved, the sex of the offspring will depend on the type of sex determination system and the type of apomixis. In species that use the [[XY sex-determination system]], parthenogenetic offspring will have two X chromosomes and are female. In species that use the [[ZW sex-determination system]] the offspring genotype may be one of ZW (female),<ref name=Lokki1975 /><ref name=Groot2003 /> ZZ (male), or WW (non-viable in most species<ref name=Booth2011 /> but a fertile,{{dubious|can't check, source is embargoed, but abstract says the mother may be WO, not WW, and doesn't indicate that the WW offspring were fertile|date=December 2011}} viable female in a few (e.g., boas)).<ref name=Booth2011 /> ZW offspring are produced by [[endoreplication]] before meiosis or by central fusion.<ref name=Lokki1975 /><ref name=Groot2003 /> ZZ and WW offspring occur either by terminal fusion<ref name=Booth2011 /> or by endomitosis in the egg cell.

In polyploid obligate parthenogens like the whiptail lizard, all the offspring are female.<ref name=Cuellar1971 />

In many hymenopteran insects such as honeybees, female eggs are produced sexually, using sperm from a drone father, while the production of further drones (males) depends on the queen (and occasionally workers) producing unfertilised eggs. This means that females (workers and queens) are always diploid, while males (drones) are always haploid, and produced parthenogenetically.

=== Facultative parthenogenesis ===
Facultative parthenogenesis is the term for when a female can produce offspring either sexually or via asexual reproduction.<ref name="bell">Bell, G. (1982). The Masterpiece of Nature: The Evolution and Genetics of Sexuality, University of California Press, Berkeley, pp. 1- 635 (see page 295). ISBN 0-520-04583-1 ISBN 978-0-520-04583-5</ref> Facultative parthenogenesis is extremely rare in nature, with only a few examples of animal taxa capable of facultative parthenogenesis.<ref name="bell" /> One of the best known examples of taxa exhibiting facultative parthenogenesis are [[mayflies]]; presumably this is the default reproductive mode of all species in this insect order.<ref>{{cite journal|doi=10.1899/10-015.1|title=Why stream mayflies can reproduce without males but remain bisexual: A case of lost genetic variation|journal=Journal of the North American Benthological Society|volume=29|issue=4|pages=1258–1266|year=2010|last1=Funk|first1=David H.|last2=Sweeney|first2=Bernard W.|last3=Jackson|first3=John K.}}</ref> Facultative parthenogenesis is believed to be a response to a lack of a viable male. A female may undergo facultative parthenogenesis if a male is absent from the habitat or if it is unable to produce viable offspring.

Facultative parthenogenesis is often incorrectly used to describe cases of accidental or spontaneous parthenogenesis in normally sexual animals.<ref name="Vanderkooi">{{cite journal | last1 = van der Kooi | first1 = C.J. | last2 = Schwander | first2 = T. | year = 2015 | title = Parthenogenesis: birth of a new lineage or reproductive accident? | journal = Current Biology | volume = 25 | issue = 15| pages = 659–651 | publisher = | jstor = | doi = 10.1016/j.cub.2015.06.055| url = https://www.researchgate.net/publication/280691646_Parthenogenesis_Birth_of_a_New_Lineage_or_Reproductive_Accident | format = PDF | accessdate = }}</ref> For example, many cases of accidental parthenogenesis in [[sharks]], some [[snakes]], [[Komodo dragon]]s and a variety of domesticated birds were widely perpetuated as facultative parthenogenesis.<ref>{{cite journal|doi=10.1159/000195678|pmid=19276631|title=Facultative Parthenogenesis in Vertebrates: Reproductive Error or Chance?|journal=Sexual Development|volume=2|issue=6|pages=290–301|year=2008|last1=Lampert|first1=K.P.}}</ref> These cases are, however, examples of accidental parthenogenesis, given the frequency of asexually produced eggs and their hatching rates are extremely low, in contrast to true facultative parthenogenesis where the majority of asexually produced eggs hatch.<ref name="bell" /><ref name="Vanderkooi" /> In addition, asexually produced offspring in vertebrates are virtually always sterile {{citation needed|date=August 2016}}, highlighting that this mode of reproduction is not adaptive, because the ability to reproduce asexually is not inherited to the next generation. The occurrence of such asexually produced eggs in sexual animals can be explained by a meiotic error, leading to eggs produced via [[automixis]].<ref name ="Vanderkooi" /><ref>Suomalainen E. et al. (1987). Cytology and Evolution in Parthenogenesis, Boca Raton, CRC Press</ref>

=== Obligate parthenogenesis ===
Obligate parthenogenesis is the process in which organisms exclusively reproduce through asexual means.<ref name=Stelzer2010>Stelzer C-P, Schmidt J, Wiedlroither A, Riss S (2010) Loss of Sexual Reproduction and Dwarfing in a Small Metazoan. PLoS.</ref> Many species have been shown to transition to obligate parthenogenesis over evolutionary time. Among these species, one of the most well documented transitions to obligate parthenogenesis was found in almost all metazoan taxa, albeit through highly diverse mechanisms. These transitions often occur as a result of inbreeding or mutation within large populations.<ref name=Scheuerl2011>Scheuerl, Thomas., et al. "Phenotypic of an Allele Causing Obligate Parthenogenesis." (2011). ''Journal of Heredity'' 2011:102(4):409–415. Web. 23 Oct. 2012</ref> There are a number of documented species, specifically salamanders and geckos, that rely on obligate parthenogenesis as their major method of reproduction. As such, there are over 80 species of unisex reptiles (mostly lizards but including a single snake species), amphibians and fishes in nature for which males are no longer a part of the reproductive process.<ref name=Booth2012>{{cite journal|last=Booth|first=W.|author2=Smith, C. F. |author3=Eskridge, P. H. |author4=Hoss, S. K. |author5=Mendelson, J. R. |author6= Schuett, G. W. |title=Facultative parthenogenesis discovered in wild vertebrates|journal=Biology Letters|year=2012|volume=8|issue=6|pages=983–985|doi=10.1098/rsbl.2012.0666|pmid=22977071|pmc=3497136}}</ref> A female will produce an ovum with a full set (two sets of genes) provided solely by the mother. Thus, a male is not needed to provide sperm to fertilize the egg. This form of asexual reproduction is thought in some cases to be a serious threat to biodiversity for the subsequent lack of gene variation and potentially decreased fitness of the offspring.<ref name="Stelzer2010" />

== Natural occurrence ==
Parthenogenesis is seen to occur naturally in [[aphid]]s, ''[[Daphnia]]'', [[rotifer]]s, [[nematode]]s and some other invertebrates, as well as in many plants. Among [[vertebrates]], strict parthenogenesis is only known to occur in lizards, snakes,<ref name=Price1992>Price, A. H. (1992). Comparative behavior in lizards of the genus ''Cnemidophorus'' (Teiidae), with comments on the evolution of parthenogenesis in reptiles. ''Copeia'', 323-331.</ref> birds<ref name="Zebra finch">{{cite journal | last1 = Schut | first1 = E. | last2 = Hemmings | first2 = N. | last3 = Birkhead | first3 = T. R. | year = 2008 | title = Parthenogenesis in a passerine bird, the Zebra Finch ''Taeniopygia guttata'' | url = | journal = Ibis | volume = 150 | issue = 1| pages = 197–199 | doi=10.1111/j.1474-919x.2007.00755.x}}</ref> and sharks,<ref name=Chapman2007>{{cite journal|last=Chapman|first=Demian D.|author2=Shivji, Mahmood S. |author3=Louis, Ed |author4=Sommer, Julie |author5=Fletcher, Hugh |author6= Prodöhl, Paulo A. |title=Virgin birth in a hammerhead shark|journal=Biology Letters|year=2007|volume=3|issue=4|pages=425–427|doi=10.1098/rsbl.2007.0189|pmid=17519185|pmc=2390672}}</ref> with fish, amphibians and reptiles exhibiting various forms of gynogenesis and hybridogenesis (an incomplete form of parthenogenesis).<ref name=UnisexualList /> The first all-female (unisexual) reproduction in [[vertebrates]] was described in the fish ''[[Poecilia formosa]]'' in 1932.<ref name=Hubbs&Hubbs1932>{{cite journal|last=Hubbs|first=C. L.|author2=Hubbs, L. C.|title=Apparent parthenogenesis in nature, in a form of fish of hybrid origin|journal=Science|year=1932|volume=76|issue=1983|pages=628–630|doi=10.1126/science.76.1983.628|pmid=17730035}}</ref> Since then at least 50 species of unisexual vertebrate have been described, including at least 20 fish, 25 lizards, a single snake species, frogs, and salamanders.<ref name=UnisexualList>Vrijenhoek, R.C., R.M. Dawley, C.J. Cole, and J.P. Bogart. 1989. A list of the known unisexual vertebrates, pp. 19-23 ''in'': Evolution and Ecology of Unisexual Vertebrates. R.M. Dawley and J.P. Bogart (eds.) Bulletin 466, New York State Museum, Albany, New York</ref> Other, usually sexual, species may occasionally reproduce parthenogenetically and [[Komodo dragon]]s; the [[hammerhead shark|hammerhead]] and [[blacktip shark]]s are recent additions to the known list of spontaneous parthenogenetic vertebrates. As with all types of [[asexual reproduction]], there are both costs (low genetic diversity and therefore susceptibility to adverse mutations that might occur) and benefits (reproduction without the need for a male) associated with parthenogenesis.

Parthenogenesis is distinct from artificial [[animal cloning]], a process where the new organism is necessarily genetically identical to the cell donor. In cloning, the [[Cell nucleus|nucleus]] of a [[diploid]] cell from a donor organism is inserted into an enucleated egg cell and the cell is then stimulated to undergo continued [[mitosis]], resulting in an organism that is genetically identical to the donor. Parthenogenesis is different, in that it originates from the genetic material contained within an egg cell and the new organism is not necessarily genetically identical to the parent.

Parthenogenesis may be achieved through an artificial process as described below under the discussion of mammals.

=== Insects ===
Parthenogenesis in insects can cover a wide range of mechanisms.<ref name="insencyc">Kirkendall, L. R. & Normark, B. (2003) ''Parthenogenesis'' in Encyclopaedia of Insects (Vincent H. Resh and R. T. Carde, Eds.) Academic Press. pp. 851–856</ref> The offspring produced by parthenogenesis may be of both sexes, only female ([[thelytoky]], e.g. aphids and some hymenopterans<ref>http://www.bioone.org/doi/abs/10.1653/024.093.0318</ref>) or only male ([[arrhenotoky]], e.g. most [[hymenopteran]]s). Both true parthenogenesis and [[pseudogamy]] ('''gynogenesis''' or '''sperm-dependent parthenogenesis''') are known to occur.<ref name="bell" /> The egg cells, depending on the species may be produced without meiosis (apomictically) or by one of the several automictic mechanisms.

A related phenomenon, polyembryony is a process that produces multiple clonal offspring from a single egg cell. This is known in some hymenopteran parasitoids and in [[Strepsiptera]].<ref name="insencyc" />

In automictic species the offspring can be haploid or diploid. Diploids are produced by doubling or fusion of gametes after meiosis. Fusion is seen in the [[Phasmatodea]], [[Hemiptera]] ([[Whitefly|Aleurodids]] and [[Coccidae]]), [[Diptera]], and some [[Hymenoptera]].<ref name="insencyc" />

In addition to these forms is hermaphroditism, where both the [[Egg (biology)|eggs]] and sperm are produced by the same individual, but is not a type of parthenogenesis. This is seen in three species of ''Icerya'' scale insects.<ref name="insencyc" />

Parasitic bacteria like ''[[Wolbachia]]'' have been noted to induce automictic thelytoky in many insect species with [[haplodiploidy|haplodiploid]] systems. They also cause gamete duplication in unfertilized eggs causing them to develop into female offspring.<ref name="insencyc" />

[[File:Plumpollen0060.jpg|thumb|left|Honey Bee on a plum blossom]]

Among species with the haplo-diploid [[sex-determination system]], such as [[hymenopteran]]s (ants, bees and wasps) and [[thysanoptera]]ns (thrips), [[Hymenopteran#Sex determination|haploid males]] are produced from unfertilized eggs. Usually eggs are laid only by the queen, but the unmated workers may also lay haploid, male eggs either regularly (e.g. stingless bees) or under special circumstances. An example of non-viable parthenogenesis is common among domesticated [[honey bee]]s. The queen bee is the only fertile female in the hive; if she dies without the possibility for a viable replacement queen, it is not uncommon for the worker bees to lay eggs. This is a result of the lack of the queen's pheromones and the pheromones secreted by uncapped brood, which normally suppress ovarian development in workers. Worker bees are unable to mate, and the unfertilized eggs produce only drones (males), which can mate only with a queen. Thus, in a relatively short period, all the worker bees die off, and the new drones follow if they have not been able to mate before the collapse of the colony. This behaviour is believed to have evolved to allow a doomed colony to produce drones which may mate with a virgin queen and thus preserve the colony's genetic progeny.

A few ants and bees are capable of producing diploid female offspring parthenogenetically. These include a honey bee subspecies from South Africa, ''[[Apis mellifera capensis]]'', where workers are capable of producing [[diploid]] eggs parthenogenetically, and replacing the queen if she dies; other examples include some species of small carpenter bee, (genus ''[[Ceratina]]''). Many [[parasitic wasp]]s are known to be parthenogenetic, sometimes due to infections by ''[[Wolbachia]]''.

The workers in five<ref name=Pearcy2004 /> ant species and the queens in some ants are known to reproduce by parthenogenesis. In ''[[Cataglyphis cursor]]'', a European [[formicinae|formicine ant]], the queens and workers can produce new queens by parthenogenesis. The workers are produced sexually.<ref name=Pearcy2004 />

In Central and South American [[electric ants]], ''Wasmannia auropunctata'', queens produce more queens through automictic parthenogenesis with central fusion. Sterile workers usually are produced from eggs fertilized by males. In some of the eggs fertilized by males, however, the fertilization can cause the female genetic material to be ablated from the zygote. In this way, males pass on only their genes to become fertile male offspring. This is the first recognized example of an animal species where both females and males can reproduce clonally resulting in a complete separation of male and female gene pools.<ref name= Fournier2005>{{cite journal |last1=Fournier |first1=Denis |last2=Estoup |first2=Arnaud |last3=Orivel |first3=Jérôme |last4=Foucaud |first4=Julien |last5=Jourdan |first5=Hervé |last6=Le Breton |first6=Julien Le |last7=Keller |first7=Laurent |title=Clonal reproduction by males and females in the little fire ant |journal=Nature |volume=435 |issue=7046 |pages=1230–4 |year=2005 |pmid=15988525 |doi=10.1038/nature03705}}</ref> As a consequence, the males will only have fathers and the queens only mothers, while the sterile workers are the only ones with both parents of both genders.

These ants get both the benefits of both asexual and sexual reproduction<ref name=Pearcy2004 /><ref name=Fournier2005 />—the daughters who can reproduce (the queens) have all of the mother's genes, while the sterile workers whose physical strength and disease resistance are important are produced sexually.

Other examples of insect parthenogenesis can be found in gall-forming aphids (e.g., ''[[Pemphigus betae]]''), where females reproduce parthenogenetically during the gall-forming phase of their life cycle and in grass [[thrips]]. In the grass thrips genus ''[[Aptinothrips]]'' there have been, despite the very limited number of species in the genus, several transitions to asexuality.<ref>CJ van der Kooi & T Schwander (2014) [https://www.researchgate.net/profile/Tanja_Schwander/publication/260836273_EVOLUTION_OF_ASEXUALITY_VIA_DIFFERENT_MECHANISMS_IN_GRASS_THRIPS_%28THYSANOPTERA_Aptinothrips_%29/links/53ff35850cf283c3583c85eb.pdf?ev=pub_int_doc_dl&origin=publication_list&inViewer=true&msrp=IBQJNWHpvxIAz3kONxRs8lTmXkKo1guqdmdPS1nMBZfNi9jW2N4vYE9azjJYBcME9kDVA%2FNkFnIUCPr6PoRwA8mV7UHkNdi%2BXuQAXGzsOF4%3D_vYneys1Jb1%2FxWwUcusStqzATbxMR6TZFR7HaHHn4s78IUjlt1FtUb2aBzYwzHRu00%2BKqO5aVfYnB9YNnlAkhDQ%3D%3D Evolution of asexuality via different mechanisms in grass thrips (Thysanoptera: Aptinothrips)] Evolution 86:1883-1893</ref>

=== Crustaceans ===
Crustacean reproduction varies both across and within species. The [[water flea]] ''[[Daphnia pulex]]'' alternates between sexual and parthenogenetic reproduction.<ref>{{cite journal |last1=Eads |first1=Brian D |last2=Colbourne |first2=John K |last3=Bohuski |first3=Elizabeth |last4=Andrews |first4=Justen |title=Profiling sex-biased gene expression during parthenogenetic reproduction in Daphnia pulex |journal=BMC Genomics |volume=8 |page=464 |year=2007 |pmid=18088424 |pmc=2245944 |doi=10.1186/1471-2164-8-464}}</ref> Among the better-known large [[decapoda|decapod]] [[crustaceans]], some crayfish reproduce by parthenogensis. "[[Marmorkrebs]]" are parthenogenetic [[crayfish]] that were discovered in the [[Fishkeeping|pet trade]] in the 1990s.<ref>{{cite journal |last1=Scholtz |first1=Gerhard |last2=Braband |first2=Anke |last3=Tolley |first3=Laura |last4=Reimann |first4=André |last5=Mittmann |first5=Beate |last6=Lukhaup |first6=Chris |last7=Steuerwald |first7=Frank |last8=Vogt |first8=GüNter |title=Ecology: Parthenogenesis in an outsider crayfish |journal=Nature |volume=421 |issue=6925 |page=806 |year=2003 |pmid=12594502 |doi=10.1038/421806a}}</ref> Offspring are genetically identical to the parent, indicating it reproduces by apomixis, i.e. parthenogenesis in which the eggs did not undergo meiosis.<ref>{{cite journal |last1=Martin |first1=Peer |last2=Kohlmann |first2=Klaus |last3=Scholtz |first3=Gerhard |title=The parthenogenetic Marmorkrebs (marbled crayfish) produces genetically uniform offspring |journal=Naturwissenschaften |volume=94 |issue=10 |pages=843–6 |year=2007 |pmid=17541537 |doi=10.1007/s00114-007-0260-0}}</ref> Spinycheek crayfish (''[[Orconectes limosus]]'') can reproduce both sexually and by parthenogenesis.<ref name=Buric2011>{{cite journal|last=Buřič|first=Miloš|author2=Hulák, Martin |author3=Kouba, Antonín |author4=Petrusek, Adam |author5=Kozák, Pavel |author6= Etges, William J. |title=A Successful Crayfish Invader Is Capable of Facultative Parthenogenesis: A Novel Reproductive Mode in Decapod Crustaceans|journal=PLoS ONE|date=31 May 2011|volume=6|issue=5|pages=e20281|doi=10.1371/journal.pone.0020281|url=http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020281|editor1-last=Etges|editor1-first=William J|pmid=21655282|pmc=3105005}}</ref> The Louisiana red swamp crayfish (''[[Procambarus clarkii]]''), which normally reproduces sexually, has also been suggested to reproduce by parthenogenesis,<ref>{{cite journal |url=http://www.biolsci.org/v04p0279.htm |vauthors=Yue GH, Wang GL, Zhu BQ, Wang CM, Zhu ZY, Lo LC |year=2008 |title=Discovery of four natural clones in a crayfish species ''Procambarus clarkii'' |journal=International Journal of Biological Sciences |volume=4 |issue=5 |pages=279–82 |pmid=18781225 |pmc=2532795 |doi=10.7150/ijbs.4.279}}</ref> although no individuals of this species have been reared this way in the lab. ''[[Artemia parthenogenetica]]'' is a species or series of populations of parthenogenetic [[brine shrimp]]s.<ref name="MuñozEtAl2010">{{cite journal|last1=Muñoz|first1=Joaquín|last2=Gómez|first2=Africa|last3=Green|first3=Andy J.|last4=Figuerola|first4=Jordi|last5=Amat|first5=Francisco|last6=Rico|first6=Ciro|last7=Moreau|first7=Corrie S.|title=Evolutionary Origin and Phylogeography of the Diploid Obligate Parthenogen ''Artemia parthenogenetica'' (Branchiopoda: Anostraca)|journal=PLoS ONE|date=4 August 2010|volume=5|issue=8|pages=e11932|doi=10.1371/journal.pone.0011932|pmid=20694140|pmc=2915914}}</ref>

===Velvet worms===
No males of ''[[Epiperipatus imthurni]]'' have been found, and specimens from [[Trinidad]] were shown to reproduce parthenogenetically. This species is the only known [[Onychophora|velvet worm]] to reproduce via parthenogenesis.<ref name="Read1988">{{cite journal |first1=V. M. St. J. |last1=Read |date=July 1988 |title=The Onychophora of Trinidad, Tobago, and the Lesser Antilles |journal=Zoological Journal of the Linnean Society |volume=93 |issue=3 |pages=225–57 |doi=10.1111/j.1096-3642.1988.tb01362.x}}</ref>

===Spiders===
At least two species of spiders in the family [[Oonopidae]] (goblin spiders), ''[[Heteroonops spinimanus]]'' and ''[[Triaeris stenaspis]]'', are thought to be parthenogenetic, as no males have ever been collected. Parthenogenetic reproduction has been demonstrated in the laboratory for ''T.&nbsp;stenaspis''.<ref name=KoreSmerPeka09>{{Cite journal |last1=Korenko |first1=Stanislav |last2=Šmerda |first2=Jakub |last3=Pekár |first3=Stano |date=2009 |title=Life-history of the parthenogenetic oonopid spider, ''Triaeris stenaspis'' (Araneae: Oonopidae) |journal=European Journal of Entomology |volume=106 |issue=2 |pages=217–223 |url=https://www.researchgate.net/publication/236201102_Life-history_of_the_parthenogenetic_oonopid_spider_Triaeris_stenaspis_Araneae_Oonopidae |accessdate=2016-04-30 |lastauthoramp=yes |doi=10.14411/eje.2009.028}}</ref>

=== Rotifers ===
In [[Bdelloidea|bdelloid]] [[rotifers]], females reproduce exclusively by parthenogenesis (obligate parthenogenesis),<ref>"Bdelloids: No sex for over 40 million years.". TheFreeLibrary. ScienceNews. Retrieved 30 April 2011.</ref> while in [[monogonont]] rotifers, females can alternate between sexual and asexual reproduction (cyclical parthenogenesis). At least in one normally cyclical parthenogenetic species obligate parthenogenesis can be inherited: a recessive allele leads to loss of sexual reproduction in homozygous offspring.<ref>{{cite journal | last1 = Stelzer | first1 = C.-P. | last2 = Schmidt | first2 = J. | last3 = Wiedlroither | first3 = A. | last4 = Riss | first4 = S. | year = 2010 | title = Loss of Sexual Reproduction and Dwarfing in a Small Metazoan | url = http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0012854;jsessionid=1881F9E65C562FF5D30907B50E7588A3.ambra01 | journal = PLoS ONE | volume = 5 | issue = 9| page = e12854 | doi=10.1371/journal.pone.0012854 | pmid=20862222| pmc = 2942836 }}</ref>

=== Flatworms ===
At least two species in the genus ''[[Dugesia]]'', flatworms in the [[Turbellaria]] sub-division of the [[phylum]] [[Platyhelminthes]], include [[polyploid]] individuals that reproduce by parthenogenesis.<ref>{{cite journal |last1=Lentati |first1=G. Benazzi |title=Amphimixis and pseudogamy in fresh-water triclads: Experimental reconstitution of polyploid pseudogamic biotypes |journal=Chromosoma |volume=20 |pages=1–14 |year=1966 |doi=10.1007/BF00331894}}</ref> This type of parthenogenesis requires mating, but the [[sperm]] does not contribute to the genetics of the offspring (the parthenogenesis is [[pseudogamous]], alternatively referred to as gynogenetic). A complex cycle of matings between diploid sexual and polyploid parthenogenetic individuals produces new parthenogenetic lines.

=== Snails ===
Several species of parthenogenetic [[gastropods]] have been studied, especially with respect to their status as [[invasive species]]. Such species include the [[New Zealand mud snail]] (''Potamopyrgus antipodarum''),<ref name=Wallace92>{{cite journal|last=Wallace|first=C.|title=arthenogenesis, sex and chromosomes in ''Potamopyrgus''|journal=Journal of Molluscan Studies|year=1992|volume=58|issue=2|pages=93–107|doi=10.1093/mollus/58.2.93}}</ref> the [[red-rimmed melania]] (''Melanoides tuberculata''),<ref name=Ben-Ami&Heller2005>{{cite journal|last=Ben-Ami|first=F.|author2=Heller, J.|title=Spatial and temporal patterns of parthenogenesis and parasitism in the freshwater snail Melanoides tuberculata|journal=Journal of Evolutionary Biology|year=2005|volume=18|issue=1|pages=138–146|doi=10.1111/j.1420-9101.2004.00791.x|pmid=15669970}}</ref> and the [[Quilted melania]] (''Tarebia granifera'').<ref name=Mirandaetal2011>{{cite journal|last=Miranda|first=Nelson A. F.|author2=Perissinotto, Renzo |author3=Appleton, Christopher C. |author4= Lalueza-Fox, Carles |title=Population Structure of an Invasive Parthenogenetic Gastropod in Coastal Lakes and Estuaries of Northern KwaZulu-Natal, South Africa|journal=PLoS ONE|year=2011|volume=6|issue=8|pages=e24337|doi=10.1371/journal.pone.0024337|pmid=21904629|pmc=3164166}}</ref>

=== Squamata ===
{{Main article|Parthenogenesis in squamata}}
[[File:Varanus komodoensis5.jpg|thumb|right|Komodo dragon, ''Varanus komodoensis'', rarely reproduces offspring via parthenogenesis.]]
Most reptiles of the [[squamata]]n order ([[lizard]]s and [[snake]]s) [[sexual reproduction|reproduce sexually]], but parthenogenesis has been observed to occur naturally in certain species of [[Cnemidophorus|whiptails]], some [[gecko]]s, [[Darevskia|rock lizards]],<ref name="reptiles" /><ref name=Darevski>Darevskii IS. 1967. Rock lizards of the Caucasus: systematics, ecology and phylogenesis of the polymorphic groups of Caucasian rock lizards of the subgenus ''Archaeolacerta''. Nauka: Leningrad [in Russian: English translation published by the Indian National Scientific Documentation Centre, New Delhi, 1978].</ref><ref name=tarkhnishvili>Tarkhnishvili DN (2012) Evolutionary History, Habitats, Diversification, and Speciation in Caucasian Rock Lizards. In: Advances in Zoology Research, Volume 2 (ed. Jenkins OP), Nova Science Publishers, Hauppauge (NY), p.79-120</ref>[[Komodo dragon]]s and snakes.<ref>[http://www.upi.com/Science_News/2015/09/21/Self-impregnated-snake-in-Missouri-has-another-virgin-birth/5631442860153/?spt=trc Self-impregnated snake in Missouri has another 'virgin birth'], UPI, 21 September 2015. Retrieved 3 October 2015.</ref> Some of these like the [[Lepidodactylus lugubris|mourning gecko]] ''Lepidodactylus lugubris'', [[Indo-Pacific gecko|Indo-Pacific house gecko]] ''Hemidactylus garnotii'', the hybrid whiptails ''[[Cnemidophorus]]'', Caucasian rock lizards ''[[Darevskia]]'', and the [[Ramphotyphlops braminus|brahminy blindsnake]], ''Indotyphlops braminus'' are unisexual and obligately parthenogenetic. Others reptiles, such as the Komodo dragon, other monitor lizards,<ref name=Wiechmann>{{cite journal |last1= Wiechmann |first1=R. |title=Observations of parthenogenesis in monitor lizards |journal=Biawak |year=2012 | volume=6 | issue=1|pages=11–21}}</ref> and some species of [[Boidae|boas]],<ref name=Booth>{{cite journal |last1=Booth |first1=W. |last2=Johnson |first2=D. H. |last3=Moore |first3=S. |last4=Schal |first4=C. |last5=Vargo |first5=E. L. |title=Evidence for viable, non-clonal but fatherless Boa constrictors |journal=Biology Letters |year=2010 |doi=10.1098/rsbl.2010.0793 |volume=7 |issue=2 |pages=253–256 |pmid=21047849 |pmc=3061174}}</ref><ref name="Booth2011" /><ref name=Kinney>{{cite journal |last1=Kinney |first1=M.E. |last2=Wack |first2=R.F. |last3=Grahn |first3=R.A. |last4= Lyons |first4=L. |title=Parthenogenesis in a Brazilian rainbow boa (''Epicrates cenchria cenchria'') |journal=Zoo Biology |year=2013 | volume=32 |issue=2 |pages=172–176 |doi=10.1002/zoo.21050|pmid=23086743 }}</ref> [[Pythonidae|pythons]],<ref name="Groot2003" /> [[Acrochordidae|filesnakes]],<ref name=Magnusson>{{cite journal |last1= Magnusson |first1=W.E. |title=Production of an embryo by an ''Acrochordus javanicus'' isolated for seven years |journal=Copeia |year=1979 |volume=1979 |issue=4 |pages=744–745 |doi=10.2307/1443886|jstor=1443886 }}</ref><ref name=Dubach>{{cite journal |last1=Dubach |first1=J. |last2=Sajewicz |first2=A. |last3=Pawley |first3=R. |title=Parthenogenesis in the Arafura filesnake (''Acrochordus arafurae'') |journal=Herpetological Natural History |year=1997 |volume=5 |issue=1 |pages=11–18}}</ref> [[garter snake|gartersnakes]]<ref name=Reynolds>{{cite journal |last1=Reynolds |first1=R.G. |last2=Booth |first2=W. |last3=Schuett |first3=G.W. |last4=Fitzpatrick |first4=B.M. |last5=Burghardt |first5=G.M. |title=Successive virgin births of viable male progeny in the checkered gartersnake, ''Thamnophis marcianus'' |journal=Biological Journal of the Linnean Society |year=2012 |volume=107| issue=3|pages=566–572 |doi=10.1111/j.1095-8312.2012.01954.x}}</ref> and [[rattlesnake]]s<ref name=Schuett>{{cite journal |last1=Schuett |first1=G.W. |last2=Fernandez |first2=P.J. |last3=Gergits |first3=W.F. |last4= Casna |first4=N.J.. |last5=Chiszar |first5=D. |last6=Smith |first6=H.M. |last7=Mitton |first7=J.B. |last8=Mackessy |first8=S.P. |last9=Odum |first9=R.A. |last10=Demlong |first10=M.J. |title=Production of offspring in the absence of males: Evidence for facultative parthenogenesis in bisexual snakes |journal=Herpetological Natural History |year=1997 |volume=5 |issue=1|pages=1–10}}</ref><ref name=Schuett2>{{cite journal |last1=Schuett |first1=G.W. |last2=Fernandez |first2=P.J. |last3=Chiszar |first3=D. |last4=Smith |first4=H.M. |title=Fatherless Sons: A new type of parthenogenesis in snakes |journal=Fauna |year=1998 |volume=1 |issue=3|pages=20–25}}</ref> were previously considered as cases of facultative parthenogenesis, but are in fact cases of accidental parthenogenesis.<ref name="Vanderkooi" />

In 2012, facultative parthenogenesis was reported in wild vertebrates for the first time by US researchers amongst captured pregnant copperhead and cottonmouth female pit-vipers.<ref>{{cite web| title = Virgin births discovered in wild snakes| date= September 12, 2012| url=http://www.bbc.co.uk/nature/19555550| accessdate = 2012-09-12 }}</ref> The Komodo dragon, which normally reproduces sexually, has also been found able to reproduce asexually by parthenogenesis.<ref>[http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2006/12/21/ndragon21.xml "No sex please, we're lizards"], Roger Highfield, Daily Telegraph, 21 December 2006</ref> A case has been documented of a Komodo dragon reproducing via sexual reproduction after a known parthenogenetic event,<ref name="The Hindu">[http://www.hindu.com/2007/01/25/stories/2007012506101400.htm Virgin birth of dragons], The Hindu, 25 January 2007. Retrieved 3 February 2007.</ref> highlighting that these cases of parthenogenesis are reproductive accidents, rather than adaptive, facultative parthenogenesis.<ref name="Vanderkooi" />

Some reptile species use a ZW chromosome system, which produces either males (ZZ) or females (ZW). Until 2010, it was thought that the ZW chromosome system used by reptiles was incapable of producing viable WW offspring, but a (ZW) female boa constrictor was discovered to have produced viable female offspring with WW chromosomes.<ref>{{cite news| url=http://news.bbc.co.uk/earth/hi/earth_news/newsid_9139000/9139971.stm | work=BBC News | first=Matt | last=Walker | title=Snake has unique 'virgin birth' | date=2010-11-03}}</ref>

Parthenogenesis has been studied extensively in the [[Cnemidophorus neomexicanus|New Mexico whiptail]] in the genus ''Cnemidophorus'' (also known as ''[[Aspidoscelis]]'') of which 15 species reproduce exclusively by parthenogenesis. These lizards live in the dry and sometimes harsh climate of the southwestern United States and northern Mexico. All these asexual species appear to have arisen through the hybridization of two or three of the sexual species in the genus leading to [[polyploid]] individuals. The mechanism by which the mixing of chromosomes from two or three species can lead to parthenogenetic reproduction is unknown. Recently, a hybrid parthenogenetic whiptail lizard was bred in the laboratory from a cross between an asexual and a sexual whiptail.<ref>{{cite journal| doi = 10.1073/pnas.1102811108| volume = 108| issue = 24| pages = 9910–9915| last = Lutes| first = Aracely A.|author2=Diana P. Baumann |author3=William B. Neaves |author4=Peter Baumann | title = Laboratory synthesis of an independently reproducing vertebrate species| journal = Proceedings of the National Academy of Sciences| accessdate = 2011-12-23| date = 2011-06-14| url = http://www.pnas.org/content/108/24/9910.abstract}}</ref> Because multiple hybridization events can occur, individual parthenogenetic whiptail species can consist of multiple independent asexual lineages. Within lineages, there is very little genetic diversity, but different lineages may have quite different genotypes.

An interesting aspect to reproduction in these asexual lizards is that mating behaviors are still seen, although the populations are all female. One female plays the role played by the male in closely related species, and mounts the female that is about to lay eggs. This behaviour is due to the hormonal cycles of the females, which cause them to behave like males shortly after laying eggs, when levels of progesterone are high, and to take the female role in mating before laying eggs, when estrogen dominates. Lizards who act out the courtship ritual have greater [[fecundity]] than those kept in isolation, due to the increase in hormones that accompanies the mounting. So, although the populations lack males, they still require sexual behavioral stimuli for ''maximum'' reproductive success.<ref>{{cite journal |last1=Crews |first1=D. |title=Behavioral Facilitation of Reproduction in Sexual and Unisexual Whiptail Lizards |journal=Proceedings of the National Academy of Sciences |volume=83 |pages=9547–50 |year=1986 |doi=10.1073/pnas.83.24.9547 |issue=24 |last2=Grassman |first2=M. |last3=Lindzey |first3=J.}}</ref>

Some lizard parthenogens show a pattern of geographic parthenogenesis, occupying high mountain areas where their ancestral forms have an inferior competition ability.<ref>Vrijenhoek RC, Parker ED. 2009. Geographical parthenogenesis: general purpose genotypes and frozen niche variation. In: Schön I, Martens K, Van Dijk P, eds. Lost sex. Berlin: Springer Publications, 99–131</ref> In Caucasian rock lizards of genus ''[[Darevskia]]'', which have six parthenogenetic forms of hybrid origin<ref name=Darevski /><ref name=tarkhnishvili /><ref>{{cite journal | last1 = Murphy | first1 = RW | last2 = Darevsky | first2 = IS | last3 = MacCulloch | first3 = RD | last4 = Fu | first4 = J | last5 = Kupriyanova | first5 = LA | last6 = Upton | first6 = DE | last7 = Danielyan | first7 = F. | year = 1997 | title = Old age, multiple formations or genetic plasticity? Clonal diversity in a parthenogenetic Caucasian rock lizard, Lacerta dahli | doi = 10.1023/A:1018392603062 | pmid = 16220367 | journal = Genetica | volume = 101 | issue = 2| pages = 125–130 }}</ref> hybrid parthenogenetic form ''D. "dahli"'' has a broader niche than either of its bisexual ancestors and its expansion throughout the Central [[Lesser Caucasus]] caused decline of the ranges of both its maternal and paternal species.<ref>{{cite journal | last1 = Tarkhnishvili | first1 = D | last2 = Gavashelishvili | first2 = A | last3 = Avaliani | first3 = A | last4 = Murtskhvaladze | first4 = M | last5 = Mumladze | first5 = L | year = 2010 | title = Unisexual rock lizard might be outcompeting its bisexual progenitors in the Caucasus | url = | journal = Biological Journal of the Linnean Society | volume = 101 | issue = 2| pages = 447–460 | doi = 10.1111/j.1095-8312.2010.01498.x }}</ref>

=== Amphibians ===
{{Main article|Parthenogenesis in amphibians}}

=== Sharks ===
Parthenogenesis in sharks has been confirmed in at least three species, the [[bonnethead]],<ref name=Chapman2007 /> the [[blacktip shark]],<ref name=Blacktip>{{cite journal|last=Chapman|first=D. D.|author2=Firchau, B. |author3=Shivji, M. S. |title=Parthenogenesis in a large-bodied requiem shark, the blacktip|journal=Journal of Fish Biology|year=2008|volume=73|issue=6|pages=1473–1477|doi=10.1111/j.1095-8649.2008.02018.x}}</ref> and the [[zebra shark]],<ref name="zebra shark">{{cite journal|last=Robinson|first=D. P.|author2=Baverstock, W. |author3=Al-Jaru, A. |author4=Hyland, K. |author5= Khazanehdari, K. A. |title=Annually recurring parthenogenesis in a zebra shark ''Stegostoma fasciatum''|journal=Journal of Fish Biology|year=2011|volume=79|issue=5|pages=1376–1382|doi=10.1111/j.1095-8649.2011.03110.x|pmid=22026614}}</ref> and reported in others.

A [[bonnethead]], a type of small [[hammerhead shark]], was found to have produced a pup, born live on 14 December 2001 at [[Henry Doorly Zoo]] in Nebraska, in a tank containing three female hammerheads, but no males. The pup was thought to have been conceived through parthenogenic means. The shark pup was apparently killed by a [[stingray]] within days of birth.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/science/nature/6681793.stm|title=Captive shark had 'virgin birth'|accessdate=2008-12-23| work=BBC News | date=2007-05-23}}</ref> The investigation of the birth was conducted by the research team from Queen's University Belfast, Southeastern University in Florida, and Henry Doorly Zoo itself, and it was concluded after DNA testing that the reproduction was parthenogenic. The testing showed the female pup's DNA matched only one female who lived in the tank, and that no male DNA was present in the pup. The pup was not a twin or clone of her mother, but rather, contained only half of her mother's DNA ("[[#Automictic_parthenogenesis|automictic parthenogenesis]]"). This type of reproduction had been seen before in bony fish, but never in cartilaginous fish such as sharks, until this documentation.

In the same year, a female [[Blacktip shark|Atlantic blacktip shark]] in Virginia reproduced via parthenogenesis.<ref name="metro">{{cite news| title='Virgin birth' for aquarium shark| url=http://www.metro.co.uk/weird/article.html?Virgin_birth_for_aquarium_shark&in_article_id=351241&in_page_id=2| publisher=[[Metro.co.uk]]| date=2008-10-10| accessdate=2008-10-10| quote=}}</ref> On 10 October 2008 scientists confirmed the second case of a virgin birth in a shark. The Journal of Fish Biology reported a study in which scientists said DNA testing proved that a pup carried by a female Atlantic blacktip shark in the Virginia Aquarium & Marine Science Center contained no genetic material from a male.<ref name=Blacktip />

In 2002, two [[white-spotted bamboo shark]]s were born at the [[Belle Isle Aquarium]] in Detroit. They hatched 15 weeks after being laid. The births baffled experts as the mother shared an aquarium with only one other shark, which was female. The female bamboo sharks had laid eggs in the past. This is not unexpected, as many animals will lay eggs even if there is not a male to fertilize them. Normally, the eggs are assumed to be inviable and are discarded. This batch of eggs was left undisturbed by the curator as he had heard about the previous birth in 2001 in Nebraska and wanted to observe whether they would hatch. Other possibilities had been considered for the birth of the Detroit bamboo sharks including thoughts that the sharks had been fertilized by a male and stored the sperm for a period of time, as well as the possibility that the Belle Isle bamboo shark is a hermaphrodite, harboring both male and female sex organs, and capable of fertilizing its own eggs, but that is not confirmed.<ref>National Geographic, (2002). Shark gives virgin birth in Detroit. Retrieved Apr. 17, 2010, from Nationalgeographic.com Web site:
http://news.nationalgeographic.com/news/2002/09/0925_020925_virginshark.html.</ref>

In 2008, a Hungarian aquarium had another case of parthenogenesis after its lone female shark produced a pup without ever having come into contact with a male shark.

The repercussions of parthenogenesis in sharks, which fails to increase the genetic diversity of the offspring, is a matter of concern for shark experts, taking into consideration conservation management strategies for this species, particularly in areas where there may be a shortage of males due to fishing or environmental pressures. Although parthenogenesis may help females who cannot find mates, it does reduce genetic diversity.

In 2011, recurring shark parthenogenesis over several years was demonstrated in a captive [[zebra shark]], a type of carpet shark.<ref name="zebra shark" /><ref>{{cite web|url=http://sharkyear.com/2011/first-virgin-birth-of-zebra-shark-in-dubai.html|title=First Virgin Birth of Zebra Shark in Dubai | publisher=Sharkyear.com}}</ref> DNA genotyping demonstrated that individual zebra sharks can switch from sexual to parthenogenetic reproduction.<ref>{{Cite journal|last=Dudgeon|first=Christine L.|last2=Coulton|first2=Laura|last3=Bone|first3=Ren|last4=Ovenden|first4=Jennifer R.|last5=Thomas|first5=Severine|date=2017-01-16|title=Switch from sexual to parthenogenetic reproduction in a zebra shark|url=http://www.nature.com/articles/srep40537|journal=Scientific Reports|language=en|volume=7|doi=10.1038/srep40537|issn=2045-2322|page=40537}}</ref>

=== Birds ===
Parthenogenesis in birds is known mainly from studies of [[domesticated turkey]]s and [[chicken]]s, although it has also been noted in the [[domestic pigeon]].<ref name="Zebra finch" /> In most cases the egg fails to develop normally or completely to hatching.<ref name="Zebra finch" /><ref name=Mittwoch>{{cite journal|last=Mittwoch|first=U|title=Parthenogenesis|journal=Journal of Medical Genetics|year=1978|volume=15|issue=3|pages=165–181|doi=10.1136/jmg.15.3.165|url=http://jmg.bmj.com/content/15/3/165.full.pdf|pmid=353283|pmc=1013674}}</ref> The first description of parthenogenetic development in a [[passerine]] was demonstrated in captive [[zebra finch]]es, although the dividing cells exhibited irregular [[Cell nucleus|nuclei]] and the eggs did not hatch.<ref name="Zebra finch" />

Parthenogenesis in turkeys appears to result from a conversion of [[haploid]] cells to [[diploid]];<ref name=Mittwoch /> most embryos produced in this way die early in development. Rarely, viable birds result from this process, and the rate at which this occurs in turkeys can be increased by [[selective breeding]],<ref>{{cite web |first=Karl |last=Nestor |year=2009 |title=Parthenogenesis in turkeys |work=The Tremendous Turkey |publisher=The Ohio State University |url=http://www.oardc.ohio-state.edu/4hpoultry/t02_pageview/The_Tremendous_Turkey_10.htm}}</ref> however male turkeys produced from parthenogenesis exhibit smaller [[testes]] and reduced fertility.<ref name=Sarvella1974>{{cite journal|last=Sarvella|first=P|title=Testes structure in normal and parthenogenetic turkeys|journal=The Journal of heredity|year=1974|volume=65|issue=5|pages=287–90|pmid=4373503}}</ref>

=== Mammals ===
There are no known cases of naturally occurring mammalian parthenogenesis in the wild. Parthenogenetic progeny of mammals would have two X chromosomes, and would therefore be female.

In 1936, [[Gregory Goodwin Pincus]] reported successfully inducing parthenogenesis in a [[rabbit]].<ref>[https://archive.org/stream/eggsofmammals00pinc/eggsofmammals00pinc_djvu.txt Full text of "The eggs of mammals"] from [[Internet Archive]]</ref> In April 2004, scientists at [[Tokyo University of Agriculture]] used parthenogenesis successfully to create [[Kaguya (mouse)|a fatherless mouse]]. Using gene targeting, they were able to manipulate two imprinted loci H19/IGF2 and DLK1/[[MEG3]] to produce bi-maternal mice at high frequency<ref name="pmid17704765">{{cite journal |last1=Kawahara |first1=Manabu |last2=Wu |first2=Qiong |last3=Takahashi |first3=Nozomi |last4=Morita |first4=Shinnosuke |last5=Yamada |first5=Kaori |last6=Ito |first6=Mitsuteru |last7=Ferguson-Smith |first7=Anne C |last8=Kono |first8=Tomohiro |title=High-frequency generation of viable mice from engineered bi-maternal embryos |journal=Nature Biotechnology |volume=25 |issue=9 |pages=1045–50 |year=2007 |pmid=17704765 |doi=10.1038/nbt1331}}</ref> and subsequently show that fatherless mice have enhanced [[longevity]].<ref name="pmid19952375">{{cite journal |last1=Kawahara |first1=M. |last2=Kono |first2=T. |title=Longevity in mice without a father |journal=Human Reproduction |volume=25 |issue=2 |pages=457–61 |year=2009 |pmid=19952375 |doi=10.1093/humrep/dep400}}</ref>

Induced parthenogenesis in [[mouse|mice]] and [[monkey]]s often results in abnormal development. This is because mammals have [[Genomic imprinting|imprinted]] genetic regions, where either the maternal or the paternal chromosome is inactivated in the offspring in order for development to proceed normally. A mammal created by parthenogenesis would have double doses of maternally imprinted genes and lack paternally imprinted genes, leading to developmental abnormalities. It has been suggested<ref name="pmid19571260">{{cite journal |last1=Bischoff |first1=S. R. |last2=Tsai |first2=S. |last3=Hardison |first3=N. |last4=Motsinger-Reif |first4=A. A. |last5=Freking |first5=B. A. |last6=Nonneman |first6=D. |last7=Rohrer |first7=G. |last8=Piedrahita |first8=J. A. |title=Characterization of Conserved and Nonconserved Imprinted Genes in Swine |journal=Biology of Reproduction |volume=81 |issue=5 |pages=906–920 |year=2009 |pmid=19571260 |pmc=2770020 |doi=10.1095/biolreprod.109.078139}}</ref> that defects in [[placenta]]l folding or interdigitation are one cause of swine parthenote abortive development. As a consequence, research on human parthenogenesis is focused on the production of [[embryonic stem cells]] for use in medical treatment, not as a reproductive strategy.

Use of an electrical or chemical stimulus can produce the beginning of the process of parthenogenesis in the asexual development of viable offspring.<ref>{{cite journal |last1=Versieren |first1=K |last2=Heindryckx |first2=B |last3=Lierman |first3=S |last4=Gerris |first4=J |last5=De Sutter |first5=P. |year=2010 |title=Developmental competence of parthenogenetic mouse and human embryos after chemical or electrical activation |journal=Reprod Biomed |volume=21 |issue=6|pages=769–775 |doi=10.1016/j.rbmo.2010.07.001 |pmid=21051286}}</ref>

[[File:Parthenogenesis - Bischoff, Steve R 2010.tif|thumb|right|400px|'''Induction of parthenogenesis in swine.'''
Parthenogenetic development of swine oocytes.<ref name="pmid19571260" /> High metaphase promoting factor (MPF) activity causes mammalian oocytes to arrest at the metaphase II stage until fertilization by a sperm. The fertilization event causes intracellular calcium oscillations, and targeted degradation of cyclin B, a regulatory subunit of MPF, thus permitting the MII-arrested oocyte to proceed through meiosis.
To initiate parthenogenesis of swine oocytes, various methods exist to induce an artificial activation that mimics sperm entry, such as calcium ionophore treatment, microinjection of calcium ions, or electrical stimulation. Treatment with cycloheximide, a non-specific protein synthesis inhibitor, enhances parthenote development in swine presumably by continual inhibition of MPF/cyclin B.<ref name=Mori>{{cite journal |last1=Mori |first1=Hironori |last2=Mizobe |first2=Yamato |last3=Inoue |first3=Shin |last4=Uenohara |first4=Akari |last5=Takeda |first5=Mitsuru |last6=Yoshida |first6=Mitsutoshi |last7=Miyoshi |first7=Kazuchika |title=Effects of Cycloheximide on Parthenogenetic Development of Pig Oocytes Activated by Ultrasound Treatment |journal=Journal of Reproduction and Development |volume=54 |issue=5 |pages=364–9 |year=2008 |pmid=18635923 |doi=10.1262/jrd.20064}}</ref> As meiosis proceeds, extrusion of the second polar is blocked by exposure to cytochalasin B. This treatment results in a diploid (2 maternal genomes) parthenote. Parthenotes can be surgically transferred to a recipient oviduct for further development, but will succumb by developmental failure after ≈30 days of gestation. The swine parthenote placentae often appears hypo-vascular and is approximately 50% smaller than biparental offspring placentae: see free image (Figure 1) in linked reference.<ref name="pmid19571260" />
]]

During oocyte development, high metaphase promoting factor (MPF) activity causes mammalian oocytes to arrest at the metaphase II stage until fertilization by a sperm. The fertilization event causes intracellular calcium oscillations, and targeted degradation of cyclin B, a regulatory subunit of MPF, thus permitting the MII-arrested oocyte to proceed through meiosis.

To initiate parthenogenesis of swine oocytes, various methods exist to induce an artificial activation that mimics sperm entry, such as calcium ionophore treatment, microinjection of calcium ions, or electrical stimulation. Treatment with cycloheximide, a non-specific protein synthesis inhibitor, enhances parthenote development in swine presumably by continual inhibition of MPF/cyclin B.<ref name=Mori /> As meiosis proceeds, extrusion of the second polar is blocked by exposure to cytochalasin B. This treatment results in a diploid (2 maternal genomes) parthenote<ref name="pmid19571260" /> Parthenotes can be surgically transferred to a recipient oviduct for further development, but will succumb to developmental failure after ≈30 days of gestation. The swine parthenote placentae often appears hypo-vascular: see free image (Figure 1) in linked reference.<ref name="pmid19571260" />

==== Humans ====
On June 26, 2007, International Stem Cell Corporation (ISCC), a California-based stem cell research company, announced that their lead scientist, Dr. Elena Revazova, and her research team were the first to intentionally create human stem cells from unfertilized human eggs using parthenogenesis. The process may offer a way for creating stem cells that are genetically matched to a particular female for the treatment of degenerative diseases that might affect her. In December 2007, Dr. Revazova and ISCC published an article<ref>{{cite journal |last1=Revazova |first1=E.S. |last2=Turovets |first2=N.A. |last3=Kochetkova |first3=O.D. |last4=Kindarova |first4=L.B. |last5=Kuzmichev |first5=L.N. |last6=Janus |first6=J.D. |last7=Pryzhkova |first7=M.V. |title=Patient-Specific Stem Cell Lines Derived from Human Parthenogenetic Blastocysts |journal=Cloning and Stem Cells |volume=9 |issue=3 |pages=432–49 |year=2007 |pmid=17594198 |doi=10.1089/clo.2007.0033}}</ref> illustrating a breakthrough in the use of parthenogenesis to produce human stem cells that are [[Homozygous#Homozygous|homozygous]] in the [[human leukocyte antigen|HLA]] region of [[DNA]]. These stem cells are called HLA homozygous parthenogenetic human stem cells (hpSC-Hhom) and have unique characteristics that would allow derivatives of these cells to be implanted into millions of people without immune rejection.<ref>{{cite journal |last1=Revazova |first1=E.S. |last2=Turovets |first2=N.A. |last3=Kochetkova |first3=O.D. |last4=Agapova |first4=L.S. |last5=Sebastian |first5=J.L. |last6=Pryzhkova |first6=M.V. |last7=Smolnikova |first7=V.Iu. |last8=Kuzmichev |first8=L.N. |last9=Janus |first9=J.D. |title=HLA Homozygous Stem Cell Lines Derived from Human Parthenogenetic Blastocysts |journal=Cloning and Stem Cells |volume=10 |issue=1 |pages=11–24 |year=2008 |pmid=18092905 |doi=10.1089/clo.2007.0063}}</ref> With proper selection of oocyte donors according to HLA [[haplotype]], it is possible to generate a bank of cell lines whose tissue derivatives, collectively, could be [[Major histocompatibility complex|MHC-matched]] with a significant number of individuals within the human population.

On August 2, 2007, after much independent investigation, it was revealed that discredited South Korean scientist [[Hwang Woo-Suk]] unknowingly produced the first human embryos resulting from parthenogenesis. Initially, Hwang claimed he and his team had extracted stem cells from cloned human embryos, a result later found to be fabricated. Further examination of the chromosomes of these cells show indicators of parthenogenesis in those extracted stem cells, similar to those found in the [[Kaguya (mouse)|mice]] created by Tokyo scientists in 2004. Although Hwang deceived the world about being the first to create artificially cloned human embryos, he did contribute a major breakthrough to stem cell research by creating human embryos using parthenogenesis.<ref>Williams, Chris. [http://www.theregister.com/2007/08/03/hwang_parthenogenesis/ "Stem cell fraudster made 'virgin birth' breakthrough: Silver lining for Korean science scandal"], ''The Register'', 3 August 2007.</ref> The truth was discovered in 2007, long after the embryos were created by him and his team in February 2004. This made Hwang the first, unknowingly, to successfully perform the process of parthenogenesis to create a human embryon and, ultimately, a human parthenogenetic stem cell line.

=== Oomycetes ===
Apomixis can apparently occur in ''[[Phytophthora]]'',<ref>{{cite journal |last1=Hurtado-Gonzales |first1=O. P. |last2=Lamour |first2=K. H. |title=Evidence for inbreeding and apomixis in close crosses ofPhytophthora capsici |journal=Plant Pathology |volume=58 |pages=715–22 |year=2009 |doi=10.1111/j.1365-3059.2009.02059.x |issue=4}}</ref> an [[Oomycetes|Oomycete]]. [[Oospore]]s derived after an experimental cross were germinated, and some of the progeny were genetically identical to one or other parent, which would imply that meiosis did not occur and the oospores developed by parthenogenesis.

== Similar phenomena ==

=== Gynogenesis ===
{{See also|Parthenogenesis in Amphibians#Gynogenesis}}
A form of asexual reproduction related to parthenogenesis is gynogenesis. Here, offspring are produced by the same mechanism as in parthenogenesis, but with the requirement that the egg merely be stimulated by the ''presence'' of [[sperm]] in order to develop. However, the sperm cell does not contribute any genetic material to the offspring. Since gynogenetic species are all female, activation of their eggs requires mating with males of a closely related species for the needed stimulus. Some [[salamander]]s of the genus ''[[Ambystoma]]'' are gynogenetic and appear to have been so for over a million years. It is believed{{Who|date=March 2010}} that the success of those salamanders may be due to rare fertilization of eggs by males, introducing new material to the gene pool, which may result from perhaps only one mating out of a million. In addition, the [[amazon molly]] is known to reproduce by gynogenesis.

=== Hybridogenesis ===
{{See also|Hybridogenesis in water frogs}}
Hybridogenesis is a mode of reproduction of [[Hybrid (biology)|hybrids]]. Hybridogenetic hybrids (for example AB [[genome]]), usually females, during [[gametogenesis]] exclude one of parental genomes (A) and produce [[gamete]]s with [[Genetic recombination|unrecombined]]<ref name="Holsbeek10" /> [[genome]] of second parental species (B), instead of containing mixed recombined parental genomes. First genome (A) is restored by [[fertilization]] of these gametes with gametes from the first species (AA, sexual host,<ref name="Holsbeek10" /> usually male).<ref name="Holsbeek10" /><ref name="Schultz69" /><ref name="Vrijenhoek98" />

So hybridogenesis is not completely asexual, but instead hemiclonal: half of genome is passed to the next generation [[Clone (cell biology)|clonally]], unrecombined, intact (B), other half [[Sexual reproduction|sexually]], recombined (A).<ref name="Holsbeek10" /><ref name="Simon03" />

This process continues, so that each generation is half (or hemi-) clonal on the mother's side and has half new genetic material from the father's side.

This form of reproduction is seen in some live-bearing fish of the genus ''[[Poeciliopsis]]''<ref name="Schultz69" /><ref name="Quattro1992" /> as well as in some of the ''[[Pelophylax]]'' spp. ("green frogs" or "waterfrogs"):
* ''[[Pelophylax kl. esculentus|P. kl. esculentus]]'' (edible frog): ''[[Pelophylax lessonae|P. lessonae]]'' × ''[[Pelophylax ridibundus|P. ridibundus]]'',<ref name="Holsbeek10" /><ref name="Beerli" /><ref name="Beukeboom1998" />
* ''[[Pelophylax kl. grafi|P. kl. grafi]]'' (Graf's hybrid frog): ''[[Pelophylax perezi|P. perezi]]'' × ''[[Pelophylax ridibundus|P. ridibundus]]''<ref name="Holsbeek10" />
* ''[[Pelophylax kl. hispanicus|P. kl. hispanicus]]'' (Italian edible frog) – unknown origin: ''[[Pelophylax bergeri|P. bergeri]]'' × ''[[Pelophylax ridibundus|P. ridibundus]]'' or ''[[Pelophylax kl. esculentus|P. kl. esculentus]]''<ref name="Holsbeek10" />
and perhaps in ''[[Pelophylax demarchii|P. demarchii]]''.

[[File:Hybridogenesis in water frogs.gif|none|thumb|500px|Example crosses between [[pool frog]] (''Pelophylax lessonae''), [[marsh frog]] (''P. ridibundus'') and their hybrid – [[edible frog]] (''P.'' kl. ''esculentus''). First one is the primary hybridisation generating hybrid, second one is most widespread type of hybridogenesis.<ref name="Holsbeek10" /><ref name="Vorburger03" />]]

Other examples where hybridogenesis is at least one of modes of reproduction include i.e.
* Iberian minnow ''[[Tropidophoxinellus alburnoides]]'' (''[[Squalius pyrenaicus]]'' × hypothetical ancestor related with [[Anaecypris hispanica]])<ref name="Pinho12" />
* spined loaches ''[[Cobitis]] hankugensis'' × ''C. longicorpus''<ref name="Saitoh04" />
* ''[[Bacillus (insect)|Bacillus]]'' stick insects [[Bacillus rossius|B. rossius]] × Bacillus grandii benazzii<ref name="Mantovani92" />

== See also ==
* [[Apomixis]] for a similar process in plants
* [[Arrhenotoky]]
* [[Miraculous births]]
* [[Parthenocarpy]] plants with seedless fruit
* [[Thelytoky]]
People
* [[Charles Bonnet]] conducted a series of experiments establishing what is now termed parthenogenesis in aphides or tree-lice
* [[Jacques Loeb]] was able to cause the eggs of [[sea urchin]]s to begin embryonic development without sperm
* [[Gregory Goodwin Pincus]] experimented with parthenogenesis

== References ==
{{Reflist |30em |refs=

<ref name="Quattro1992">{{cite journal| issn = 0027-8424 | volume = 89| issue = 1| pages = 348–352| last = Vrijenhoek| first = J M|author2=J C Avise |author3=R C Vrijenhoek | title = An Ancient Clonal Lineage in the Fish Genus ''Poeciliopsis'' (Atheriniformes: Poeciliidae)| journal = Proceedings of the National Academy of Sciences USA| accessdate = 2012-03-30| date = 1992-01-01| url = http://www.pnas.org/content/89/1/348| bibcode = 1992PNAS...89..348Q| doi = 10.1073/pnas.89.1.348 | pmid=11607248 | pmc=48234}}</ref>

<ref name="Beerli">{{cite web |title=Hybridogenesis in Water Frogs |url=http://www.tolweb.org/notes/?note_id=579 |publisher=tolweb.org}}</ref>

<ref name="Beukeboom1998">{{cite journal| doi = 10.1046/j.1420-9101.1998.11060755.x| issn = 1420-9101| volume = 11| issue = 6| pages = 755–782| last = Beukeboom| first = L. W|author2=R. C Vrijenhoek| title = Evolutionary genetics and ecology of sperm‐dependent parthenogenesis| journal = Journal of Evolutionary Biology| year = 1998}}</ref>

<ref name="Schultz69">{{cite journal |last=Schultz |first=R. Jack |date=November–December 1969 |title=Hybridization, unisexuality, and polyploidy in the teleost ''Poeciliopsis'' (Poeciliidae) and other vertebrates |journal=The American Naturalist |volume=103 |issue=934 |pages=605–619 |jstor=2459036 |doi=10.1086/282629 }}</ref>

<ref name="Holsbeek10">{{cite journal |last=Holsbeek |first=G. |last2=Jooris |first2=R. |date=2010 |title=Potential impact of genome exclusion by alien species in the hybridogenetic water frogs (''Pelophylax esculentus'' complex) |journal=Biological Invasions |volume=12 |pages=1–13 |publisher=Springer Netherlands |url= |doi=10.1007/s10530-009-9427-2 |issn=1387-3547 }}</ref>

<ref name="Vorburger03">{{cite journal |last=Vorburger |first=Christoph |last2=Reyer |first2=Heinz-Ulrich |date=2003 |title=A genetic mechanism of species replacement in European waterfrogs? |journal=Conservation Genetics |volume=4 |issue=2 |pages=141–155 |publisher=Kluwer Academic Publishers |url=http://www.zool.uzh.ch/static/research/oekologie/literatur/pdf05_01/Vorburger2003CG_4.pdf |doi=10.1023/A:1023346824722 |issn=1566-0621 |accessdate=2015-06-21 }}</ref>

<ref name="Pinho12">{{cite journal |last=Inácio |first=A |last2=Pinho |first2=J |last3=Pereira |first3=PM |last4=Comai |first4=L |last5=Coelho |first5=MM |year=2012 |title= Global Analysis of the Small RNA Transcriptome in Different Ploidies and Genomic Combinations of a Vertebrate Complex – The ''Squalius alburnoides'' |journal=PLoS ONE |volume=7 |issue=7: e41158 |pages=359–368 |url=http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0041158 |doi=10.1371/journal.pone.0041158 |accessdate=2015-06-24 |pmid=22815952 |pmc=3399795}}</ref>

<ref name="Saitoh04">{{cite journal |last=Saitoh |first=K |last2=Kim |first2=I-S |last3=Lee |first3=E-H |year=2004 |title= Mitochondrial gene introgression between spined loaches via hybridogenesis |journal=Zoological Science |volume=21 |issue=7 |pages=795–798 |url=http://dx.doi.org/10.2108/zsj.21.795 |doi=10.2108/zsj.21.795 |pmid=15277723 |accessdate=2015-06-24}}</ref>

<ref name="Mantovani92">{{cite journal |last=Mantovani |first=Barbara |last2=Scali |first2=Valerio |year=1992 |title= Hybridogenesis and androgenesis in the stick-insect ''Bacillus rossius''-''Grandii benazzii'' (Insecta, Phasmatodea) |journal=Evolution |volume=46 |issue=3 |pages=783–796 |url=http://dx.doi.org/10.2307/2409646 |doi=10.2307/2409646 |accessdate=2015-06-24|jstor=2409646 }}</ref>

<ref name="Vrijenhoek98">{{cite book |last=Vrijenhoek |first=Robert C. |editor-last=Knobil |editor-first=Ernst |editor2-last=Neill |editor2-first=Jimmy D. |date=1998 |chapter=Parthenogenesis and Natural Clones |title=Encyclopedia of Reproduction |volume=3 |publisher=Academic Press |isbn=978-0-12-227020-8 |pages=695–702 |chapterurl=http://www.mbari.org/staff/vrijen/PDFS/Vrijen_1999%20EncRep.pdf }}</ref>

<ref name="Simon03">{{cite journal |last=Simon |first=J.-C. |last2=Delmotte |first2=F. |last3=Rispe |first3=C. |last4=Crease |first4=T. |year=2003 |title=Phylogenetic relationships between parthenogens and their sexual relatives: the possible routes to parthenogenesis in animals |journal=Biological Journal of the Linnean Society |volume=79 |pages=151–163 |url=http://exa.unne.edu.ar/biologia/embriologia.animal/public_html/Bibliografia%20recomendada/Origen%20de%20la%20partenogenesis.pdf |accessdate=2015-06-21|doi=10.1046/j.1095-8312.2003.00175.x}}</ref>

}}

== Further reading ==
* Dawley, Robert M. & Bogart, James P. (1989). ''Evolution and Ecology of Unisexual Vertebrates''. Albany, New York: New York State Museum. ISBN 1-55557-179-4.
*{{cite journal |last1=Fangerau |first1=H |title=Can artificial parthenogenesis sidestep ethical pitfalls in human therapeutic cloning? An historical perspective |journal=Journal of Medical Ethics |volume=31 |issue=12 |pages=733–5 |year=2005 |pmid=16319240 |pmc=1734065 |doi=10.1136/jme.2004.010199}}
* Futuyma, Douglas J. & Slatkin, Montgomery. (1983). ''Coevolution''. Sunderland, Mass: Sinauer Associates. ISBN 0-87893-228-3.
*{{cite journal |last1=Hore |first1=T |last2=Rapkins |first2=R |last3=Graves |first3=J |title=Construction and evolution of imprinted loci in mammals |journal=Trends in Genetics |volume=23 |issue=9 |pages=440–8 |year=2007 |pmid=17683825 |doi=10.1016/j.tig.2007.07.003}}
*{{cite journal|author1=Kono, T. |author2=Obata, Y. |author3=Wu, Q. |author4=Niwa, K. |author5=Ono, Y. |author6=Yamamoto, Y. |author7=Park, E.S. |author8=Seo, J.-S. |author9=Ogawa, H. |year=2004 |title= Birth of parthenogenetic mice that can develop to adulthood |journal=Nature |volume=428 |issue=6985 |pages=860–864 |doi=10.1038/nature02402 |pmid=15103378}}
* Maynard Smith, John. (1978). ''The Evolution of Sex''. Cambridge: Cambridge University Press. ISBN 0-521-29302-2.
* Michod, Richard E. & Levin, Bruce R. (1988). ''The Evolution of Sex''. Sunderland, Mass: Sinauer Associates. ISBN 0-87893-459-6.
*{{cite journal |last1=Schlupp |first1=Ingo |title=The Evolutionary Ecology of Gynogenesis | journal=Annual Review of Ecology, Evolution, and Systematics |volume=36 |pages=399–417 |year=2005 |doi=10.1146/annurev.ecolsys.36.102003.152629}}
*{{cite journal |last1=Simon |first1=J |title=Ecology and evolution of sex in aphids |journal=Trends in Ecology & Evolution |volume=17 |pages=34–9 |year=2002 |doi=10.1016/S0169-5347(01)02331-X |last2=Rispe |first2=Claude |last3=Sunnucks |first3=Paul}}
* Stearns, Stephan C. (1988). ''The Evolution of Sex and Its Consequences'' (Experientia Supplementum, Vol. 55). Boston: Birkhauser. ISBN 0-8176-1807-4.

== External links ==
* [http://www.utexas.edu/research/crewslab/index.html Reproductive behavior in whiptails at Crews Laboratory]
* [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AsexualReproduction.html Types of asexual reproduction]
* [http://oregonstate.edu/instruct/ans-tparth/ Parthenogenesis in Incubated Turkey Eggs] from Oregon State University
* [http://news.nationalgeographic.com/news/2006/12/061220-virgin-dragons.html National Geographic NEWS: Virgin Birth Expected at Christmas – By Komodo Dragon]
* [http://news.bbc.co.uk/2/hi/science/nature/6196225.stm BBC NEWS: 'Virgin births' for giant lizards (Komodo dragon)]
* [http://uk.reuters.com/article/idUKL243822920070125 REUTERS: Komodo dragon proud mum (and dad) of five]
* [http://www.msnbc.msn.com/id/18809674/ Female sharks capable of virgin birth]
* [http://www.msnbc.msn.com/id/27107721/ Scientists confirm shark's ‘virgin birth’ Article by Steve Szkotak AP updated 1:49 a.m. ET, Fri., Oct. 10, 2008]


[[Category:Asexual reproduction in animals]]
[[Category:Asexual reproduction in animals]]

Revision as of 14:26, 27 February 2017

For a similar process in plants, rather than animals, see Apomixis.
Not to be confused with Pathogenesis.
The asexual, all-female whiptail species Cnemidophorus neomexicanus (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males C. inornatus (left) and C. tigris (right), which hybridized naturally to form the C. neomexicanus species.

Parthenogenesis Is A Very Very Very Very Sick method Ever. And also A good Friend Of Mariyam Agha

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