Editing Komodo dragon (section)

====Parthenogenesis====
{{Main|Parthenogenesis}}
[[File:Parthkomodo.jpg|thumb|right|[[Parthenogenetic]] baby Komodo dragon, [[Chester Zoo]], England]]
A Komodo dragon at [[London Zoo]] named Sungai laid a clutch of eggs in late 2005 after being separated from male company for more than two years. Scientists initially assumed she had been able to store [[spermatozoon|sperm]] from her earlier encounter with a male, an [[adaptation]] known as [[superfecundation]].<ref>{{cite news |author=Morales, Alex |publisher=[[Bloomberg Television]] |url=https://www.bloomberg.com/apps/news?pid=20601082&sid=apLYpeppu8ag&refer=canada |title=Komodo Dragons, World's Largest Lizards, Have Virgin Births |access-date=28 March 2008 |date=20 December 2006 |url-status=dead |archive-url=https://web.archive.org/web/20071008112514/http://www.bloomberg.com/apps/news?pid=20601082 |archive-date=8 October 2007 }}</ref> On 20 December 2006, it was reported that Flora, a captive Komodo dragon living in the [[Chester Zoo]] in England, was the second known Komodo dragon to have laid unfertilised eggs: she laid 11 eggs, and seven of them hatched, all of them male.<ref>Notice by her cage in [[Chester Zoo]] in England</ref> Scientists at [[Liverpool University]] in England performed genetic tests on three eggs that collapsed after being moved to an incubator, and verified Flora had never been in physical contact with a male dragon. After Flora's eggs' condition had been discovered, testing showed Sungai's eggs were also produced without outside fertilization.<ref>{{cite news |url=https://www.timesonline.co.uk/tol/news/uk/article759338.ece |title=Wise men testify to Dragon's virgin birth |access-date=26 November 2007 |work=[[The Times]] | location=London | first=Mark | last=Henderson | date=21 December 2006}}</ref> On 31 January 2008, the [[Sedgwick County Zoo]] in [[Wichita, Kansas]], became the first zoo in the Americas to document [[parthenogenesis]] in Komodo dragons. The zoo has two adult female Komodo dragons, one of which laid about 17 eggs on 19–20 May 2007. Only two eggs were incubated and hatched due to space issues; the first hatched on 31 January 2008, while the second hatched on 1 February. Both hatchlings were males.<ref>{{cite web |publisher=[[Sedgwick County Zoo]] |url=http://www.scz.org/n_recent.html |archive-url=https://web.archive.org/web/20080211184900/http://www.scz.org/n_recent.html |archive-date=11 February 2008 |title=Recent News – Sedgwick County Zoo |access-date=12 February 2008}}</ref><ref>{{cite web |publisher=[[NBC News]] |url=https://www.nbcnews.com/id/wbna23058689 |title=Komodo dragons hatch with no male involved |access-date=12 February 2008|date=8 February 2008 }}</ref>

Komodo dragons have the [[ZW sex-determination system|ZW]] chromosomal [[sex-determination system]], as opposed to the [[XY sex-determination system|mammalian XY system]]. Male progeny prove Flora's unfertilized eggs were [[haploid]] (n) and doubled their chromosomes later to become [[diploid]] (2n) (by being fertilized by a [[polar body]], or by chromosome duplication without [[cell division]]), rather than by her laying diploid eggs by one of the [[meiosis]] reduction-divisions in her [[ovaries]] failing. When a female Komodo dragon (with ZW sex chromosomes) reproduces in this manner, she provides her progeny with only one chromosome from each of her pairs of chromosomes, including only one of her two sex chromosomes. This single set of chromosomes is duplicated in the egg, which develops parthenogenetically. Eggs receiving a Z [[chromosome]] become ZZ (male); those receiving a W chromosome become WW and fail to develop,<ref name="ZW">{{cite news |work=BBC News |url=http://news.bbc.co.uk/2/hi/science/nature/6196225.stm |title=Virgin births for giant lizards |access-date=13 March 2008 |date=20 December 2006}}</ref><ref>{{cite magazine |magazine=Scientific American |url=http://www.sciam.com/article.cfm?id=strange-but-true-komodo-d |title=Strange but True: Komodo Dragons Show that "Virgin Births" Are Possible: Scientific American |access-date=24 March 2008}}</ref> meaning that only males are produced by parthenogenesis in this species.[[File:COLLECTIE TROPENMUSEUM Varanus komodoensis die geplaagd wordt TMnr 10006427.jpg|thumb|Humans handling a komodo dragon]]It has been hypothesised that this reproductive adaptation allows a single female to enter an isolated [[ecological niche]] (such as an island) and by [[parthenogenesis]] produce male offspring, thereby establishing a sexually reproducing population (via reproduction with her offspring that can result in both male and female young).<ref name="ZW" /> Despite the advantages of such an adaptation, zoos are cautioned that parthenogenesis may be detrimental to genetic diversity.<ref name="pmid">{{cite journal |vauthors=Watts PC, Buley KR, Sanderson S, Boardman W, Ciofi C, Gibson R |title=Parthenogenesis in Komodo Dragons |journal=Nature |volume=444 |issue=7122 |pages=1021–22 |date=December 2006 |pmid=17183308 |doi=10.1038/4441021a |issn=0028-0836|bibcode=2006Natur.444.1021W |s2cid=4311088 }}</ref>