Editing Gamete (section)

== Evolution ==
{{Main|Evolution of sexual reproduction}}

It is generally accepted that [[isogamy]] is the ancestral state from which [[anisogamy]] and [[oogamy]] evolved, although its evolution has left no fossil records.<ref name="Pitnick-2008">{{cite book| vauthors = Pitnick SS, Hosken DJ, Birkhead TR |author-link3=Tim Birkhead |url=https://books.google.com/books?id=kctYNbO1fE0C&q=isogamy+in+multicellular+organisms&pg=PA44|title=Sperm Biology: An Evolutionary Perspective |publisher=Academic Press|year=2008|isbn=978-0-08-091987-4|pages=43–44}}</ref><ref>{{Cite book| vauthors = Awasthi AK |url=https://books.google.com/books?id=r0h1DwAAQBAJ&q=isogamy+generally+accepted&pg=PA363|title=Textbook of Algae|publisher=Vikas Publishing House|isbn=978-93-259-9022-7|pages=363|language=en}}</ref><ref>{{Cite book|vauthors=Dusenbery DB|url=https://books.google.com/books?id=QCrimQJu1RAC|title=Living at Micro Scale: The Unexpected Physics of Being Small|date=2009|publisher=Harvard University Press|isbn=978-0-674-03116-6|pages=309|language=en}}{{Dead link|date=May 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> There are almost invariably only two gamete types, all analyses showing that intermediate gamete sizes are eliminated due to selection.<ref>{{Cite book| vauthors = Stearns SC |url=https://books.google.com/books?id=1cQACAAAQBAJ|title=The Evolution of Sex and its Consequences|date=2013-11-21|publisher=Birkhäuser|isbn=978-3-0348-6273-8|pages=21, 81–82|language=en|author-link=Stephen C. Stearns}}</ref><ref name="Lehtonen">{{cite journal | vauthors = Lehtonen J, Parker GA | title = Gamete competition, gamete limitation, and the evolution of the two sexes | journal = Molecular Human Reproduction | volume = 20 | issue = 12 | pages = 1161–1168 | date = December 2014 | pmid = 25323972 | doi = 10.1093/molehr/gau068 | author-link2 = Geoff Parker | doi-access = free }}</ref> Since intermediate sized gametes do not have the same advantages as small or large ones,<ref>{{Cite book| vauthors = Campbell A |url=https://books.google.com/books?id=2FJoAgAAQBAJ&q=intermediate+gamete&pg=PA45|title=A Mind Of Her Own: The evolutionary psychology of women|date=2013-05-16|publisher=OUP Oxford|isbn=978-0-19-164701-7|pages=45|language=en}}</ref> they do worse than small ones in mobility and numbers, and worse than large ones in supply.<ref>{{cite journal | vauthors = Bachtrog D, Mank JE, Peichel CL, Kirkpatrick M, Otto SP, Ashman TL, Hahn MW, Kitano J, Mayrose I, Ming R, Perrin N, Ross L, Valenzuela N, Vamosi JC | title = Sex determination: why so many ways of doing it? | journal = PLOS Biology | volume = 12 | issue = 7 | pages = e1001899 | date = July 2014 | pmid = 24983465 | pmc = 4077654 | doi = 10.1371/journal.pbio.1001899 | s2cid = 3741933 | doi-access = free | author-link2 = Judith Mank }}</ref>