Isogamy

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Not to be confused with Isogyny, marriage between people of similar status or age
Different forms of isogamy: A) isogamy of motile cells, B) isogamy of non-motile cells, C) conjugation.

Isogamy is a form of sexual reproduction that involves gametes of similar morphology (generally similar in shape and size), found in most unicellular organisms.[1] Because both gametes look alike, they generally cannot be classified as male or female.[2] Instead, organisms undergoing isogamy are said to have different mating types, most commonly noted as "+" and "−" strains.[3]

Etymology[]

Isogamy means equal marriage.[4] The term isogamous was first used in the year 1887.[5]

Characteristics of isogamous species[]

Isogamous species often have two mating types. Some isogamous species have more than two mating types, but the number is usually lower than ten. In some extremely rare cases a species can have thousands of mating types. In all cases, fertilization occurs when gametes of two different mating types fuse to form a zygote.[6]

Evolution[]

It is generally accepted that isogamy is an ancestral state for anisogamy.[7]

It appears that isogamy was the first stage of sexual reproduction. In several lineages (plants, animals), this form of reproduction evolved independently to anisogamous species with gametes of male and female types to oogamous species in which the female gamete is very much larger than the male and has no ability to move. This pattern may have been driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproduction.[8]

Isogamy is connected to unicellular species, although it is possible that isogamy is evolutionarily stable in multicellular species.[1]

Occurrence[]

Almost all unicellular organisms are isogamous.[9] Isogamy is considered restricted to fungi, algae, and Protista.[10] Many fungi are isogamous.[11]

Many species of Chlorophyceae are isogamous. It is typical in genera such as Ulva, Hydrodictyon, Tetraspora, Zygnema, Spirogyra, Ulothrix, and Chlamydomonas.[12]

See also[]

Biology[]

Social anthropology[]

Notes and references[]

  1. ^ a b Lehtonen, Jussi; Kokko, Hanna; Parker, Geoff A. (2016-10-19). "What do isogamous organisms teach us about sex and the two sexes?". Philosophical Transactions of the Royal Society B: Biological Sciences. 371 (1706). doi:10.1098/rstb.2015.0532. ISSN 0962-8436. PMC 5031617. PMID 27619696.
  2. ^ Sawada, Hitoshi; Inoue, Naokazu; Iwano, Megumi (2014-02-07). Sexual Reproduction in Animals and Plants. Springer. p. 216. ISBN 978-4-431-54589-7.{{cite book}}: CS1 maint: date and year (link)
  3. ^ Kumar R, Meena M, Swapnil P (2019). "Anisogamy". In Vonk J, Shackelford T (eds.). Encyclopedia of Animal Cognition and Behavior. Cham: Springer International Publishing. pp. 1–5. doi:10.1007/978-3-319-47829-6_340-1. ISBN 978-3-319-47829-6. Archived from the original on 4 November 2020. Anisogamy can be defined as a mode of sexual reproduction in which fusing gametes, formed by participating parents, are dissimilar in size.
  4. ^ Encyclopedia of Evolutionary Biology. Vol. 2. Academic Press. 2016-04-14. p. 212. ISBN 978-0-12-800426-5.
  5. ^ "Definition of ISOGAMOUS". www.merriam-webster.com. Retrieved 2021-09-14.
  6. ^ Krumbeck, Yvonne; Constable, George W. A.; Rogers, Tim (2020-02-26). "Fitness differences suppress the number of mating types in evolving isogamous species". Royal Society Open Science. 7 (2): 192126. arXiv:1906.07117. Bibcode:2020RSOS....792126K. doi:10.1098/rsos.192126. ISSN 2054-5703. PMC 7062084. PMID 32257356.
  7. ^ Pitnick, Scott S.; Hosken, Dave J.; Birkhead, Tim R. (2008-11-21). Sperm Biology: An Evolutionary Perspective. Academic Press. pp. 43–45. ISBN 978-0-08-091987-4.
  8. ^ Dusenbery, David B. (2009). Living at Micro Scale, Chapter 20. Harvard University Press, Cambridge, Massachusetts ISBN 978-0-674-03116-6.
  9. ^ Bell, Graham (2008). Selection: The Mechanism of Evolution. OUP Oxford. p. 439. ISBN 978-0-19-856972-5.
  10. ^ Togashi, Tatsuya; Cox, Paul Alan (2011-04-14). The Evolution of Anisogamy: A Fundamental Phenomenon Underlying Sexual Selection. Cambridge University Press. p. 96. ISBN 978-1-139-50082-1.
  11. ^ Heitman, Joseph; Howlett, Barbara J.; Crous, Pedro W.; Stukenbrock, Eva H.; James, Timothy Yong; Gow, Neil A. R. (2020-07-10). The Fungal Kingdom. John Wiley & Sons. p. 149. ISBN 978-1-55581-958-3.
  12. ^ Sharma, O. P. (1986-01-01). Textbook of Algae. Tata McGraw-Hill Education. p. 130. ISBN 978-0-07-451928-8.
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