Editing Platypus (section)

=== Genome ===
[[File:Platypus skeleton Pengo.jpg|thumb|Platypus skeleton]]

Because of the early divergence from the [[Theria|therian mammals]] and the low numbers of extant monotreme species, the platypus is a frequent subject of research in evolutionary biology. In 2004, [[research]]ers at the [[Australian National University]] discovered the platypus has ten [[sex chromosome]]s, compared with two (XY) in most other mammals. These ten chromosomes form five unique pairs of XY in males and XX in females, i.e. males are X{{sub|1}}Y{{sub|1}}X{{sub|2}}Y{{sub|2}}X{{sub|3}}Y{{sub|3}}X{{sub|4}}Y{{sub|4}}X{{sub|5}}Y{{sub|5}}.<ref name="discover">{{cite web|url=http://discovermagazine.com/2005/apr/sex-ys-platypuses0425/|title=Sex, Ys, and Platypuses|publisher=Discover|first=Jocelyn|last=Selim|date=25 April 2005|access-date=7 May 2008|archive-date=16 May 2008|archive-url=https://web.archive.org/web/20080516233225/http://discovermagazine.com/2005/apr/sex-ys-platypuses0425|url-status=live}}</ref> One of the X chromosomes of the platypus has great homology to the bird Z chromosome.<ref>{{Cite journal|author1=Frank Grützner|author2=Willem Rens|author3=Enkhjargal Tsend-Ayush|author4=Nisrine El-Mogharbel|author5=Patricia C. M. O'Brien|author6=Russell C. Jones|author7=Malcolm A. Ferguson-Smith|author8=Jennifer A. Marshall Graves|title=In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes|journal=Nature|volume=432|issue=7019|pages=913–917|date=16 December 2004|doi=10.1038/nature03021|pmid=15502814|bibcode=2004Natur.432..913G|s2cid=4379897}}
</ref> The platypus genome also has both reptilian and mammalian genes associated with egg fertilisation.<ref name="draft_genome">{{cite journal| journal = Nature| volume = 453| issue = 7192| pages = 175–183| title = Genome analysis of the platypus reveals unique signatures of evolution| date = 8 May 2008| doi = 10.1038/nature06936| author = Warren, Wesley C.| pmid = 18464734| pmc = 2803040 |display-authors=etal|bibcode=2008Natur.453..175W}}</ref><ref>{{cite journal |title=Beyond the Platypus Genome – 2008 Boden Research Conference |journal=Reprod Fertil Dev |volume=21 |issue=8 |pages=i–ix, 935–1027 |year=2009 |url=http://www.publish.csiro.au/nid/44/issue/4849.htm |access-date=3 March 2012 |archive-date=21 November 2015 |archive-url=https://web.archive.org/web/20151121130525/http://www.publish.csiro.au/nid/44/issue/4849.htm |url-status=live }}</ref> Though the platypus lacks the mammalian sex-determining gene [[SRY]], a study found that the mechanism of sex determination is the [[Anti-Müllerian hormone|AMH gene]] on the oldest [[Y chromosome]].<ref>{{cite journal|last1=Cortez|first1=Diego|last2=Marin|first2=Ray|last3=Toledo-Flores|first3=Deborah|last4=Froidevaux|first4=Laure|last5=Liechti|first5=Angélica|last6=Waters|first6=Paul D.|last7=Grützner|first7=Frank|last8=Kaessmann|first8=Henrik|year=2014|title=Origins and functional evolution of Y chromosomes across mammals|journal=Nature|volume=508|issue=7497|pages=488–493|doi=10.1038/nature13151|pmid=24759410|bibcode=2014Natur.508..488C|s2cid=4462870}}</ref><ref>{{cite news|last1=Salleh|first1=Anna|title=Platypus Sex 'Master Switch' Identified|url=http://www.abc.net.au/science/articles/2014/05/05/3994897.htm|publisher=Australian Broadcasting Corporation|date=5 May 2014|access-date=5 June 2014|archive-date=6 July 2016|archive-url=https://web.archive.org/web/20160706211627/http://www.abc.net.au/science/articles/2014/05/05/3994897.htm|url-status=live}}</ref> A draft version of the platypus genome sequence was published in ''[[Nature (journal)|Nature]]'' on 8{{spaces}}May 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians, and fish. More than 80% of the platypus's genes are common to the other mammals whose genomes have been sequenced.<ref name="draft_genome" /> An updated genome, the most complete on record, was published in 2021, together with the genome of the [[short-beaked echidna]].<ref>{{cite journal |last1=Zhou |first1=Yang |last2=Shearwin-Whyatt |first2=Linda |last3=Li |first3=Jing |last4=Song |first4=Zhenzhen |last5=Hayakawa |first5=Takashi |last6=Stevens |first6=David |last7=Fenelon |first7=Jane C. |last8=Peel |first8=Emma |last9=Cheng |first9=Yuanyuan |last10=Pajpach |first10=Filip |last11=Bradley |first11=Natasha |last12=Suzuki |first12=Hikoyu |last13=Nikaido |first13=Masato |last14=Damas |first14=Joana |last15=Daish |first15=Tasman |last16=Perry |first16=Tahlia |last17=Zhu |first17=Zexian |last18=Geng |first18=Yuncong |last19=Rhie |first19=Arang |last20=Sims |first20=Ying |last21=Wood |first21=Jonathan |last22=Haase |first22=Bettina |last23=Mountcastle |first23=Jacquelyn |last24=Fedrigo |first24=Olivier |last25=Li |first25=Qiye |last26=Yang |first26=Huanming |last27=Wang |first27=Jian |last28=Johnston |first28=Stephen D. |last29=Phillippy |first29=Adam M. |last30=Howe |first30=Kerstin |last31=Jarvis |first31=Erich D. |last32=Ryder |first32=Oliver A. |last33=Kaessmann |first33=Henrik |last34=Donnelly |first34=Peter |last35=Korlach |first35=Jonas |last36=Lewin |first36=Harris A. |last37=Graves |first37=Jennifer |last38=Belov |first38=Katherine |last39=Renfree |first39=Marilyn B. |last40=Grutzner |first40=Frank |last41=Zhou |first41=Qi |last42=Zhang |first42=Guojie |title=Platypus and echidna genomes reveal mammalian biology and evolution |journal=Nature |date=29 April 2021 |volume=592 |issue=7856 |pages=756–762 |doi=10.1038/s41586-020-03039-0 |pmid=33408411 |pmc=8081666 |bibcode=2021Natur.592..756Z |doi-access=free }}</ref>