Sexual reproduction
Sexual reproduction combines gametes to create genetically diverse offspring.
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Sexual reproduction involves a complex life cycle where haploid gametes combine to form a diploid zygote.[1] Among multicellular eukaryotes, the life cycle that appears most frequently is sexual reproduction, which is found in animals, fungi, and plants.[2] Prokaryotes like bacteria and archaea, which are unicellular and lack cell nuclei, do not undergo sexual reproduction.[2]
Quick Facts
- First fossil evidence
- Stenian period, about 1.05 billion years old
- Occurs in
- Most multicellular eukaryotes (animals, fungi, plants) and some unicellular eukaryotes
- Does not occur in
- Prokaryotes (bacteria and archaea)
- Cost
- Two-fold cost of sex (50% fitness disadvantage)
- Advantage
- Increases genetic diversity and impedes accumulation of harmful mutations
Facts from the source article.
Key facts and history
Homologous chromosomes pair up and exchange genetic information during recombination, increasing genetic diversity.[3] A 2014 article notes that nearly all observable living organisms are based on sexual reproduction, despite it being far less efficient than non-sexual reproduction.[4] The process called meiosis involves diploid precursor cells dividing to yield haploid cells.[3] After DNA replication produces four chromosome copies, two successive cell divisions create haploid gametes.[3]
Fossil evidence from the Stenian period, roughly 1.05 billion years ago, provides the earliest known indication of sexual reproduction in eukaryotes.[5] Because asexual reproduction enables every new organism to produce its own young, it should theoretically outcompete sexual reproduction, making the latter's evolution a paradox.[6] Sexual selection is a form of natural selection where certain individuals achieve greater reproductive success than others by being more effective at obtaining mates.[7]
What the cited sources add
The U.S. Forest Service account explains that fern sperm swim through a film of water to fertilize eggs in the female structure.[8] In most ferns, sperm from one gametophyte typically fertilizes the egg of a different gametophyte.[8] A 2014 article states that Darwin's theory of sexual selection was revolutionary but he could never demonstrate it.[4] The same article notes that examples of traits promoted by sexual selection include the antlers of elk and deer.[4]
Sexual selection exerts a powerful evolutionary pressure and can proceed faster than natural selection.[4]
Gallery
References
- Wikipedia, "Sexual reproduction" (CC BY-SA 4.0), which cites: John Maynard Smith & Eörz Szathmáry, The Major Transitions in Evolution, W. H. Freeman and Company, 1995, p 149; Chalker, "Epigenetics of Ciliates", Cold Spring Harbor Perspectives in Biology, 2013; Can Song, "Polyploid Organisms", Science China Life Sciences, 2012, p. 301–311 (original not read by us) en.wikipedia.org
- Wikipedia, "Sexual reproduction" (CC BY-SA 4.0), which cites: Nieuwenhuis, "The frequency of sex in fungi", Philosophical Transactions B, October 19, 2016; Woods, "Flowering Plants", Encyclopedia of Life, June 19, 2012; Chalker, "Epigenetics of Ciliates", Cold Spring Harbor Perspectives in Biology, 2013; Knop, "Yeast cell morphology and sexual reproduction – A short overview and some considerations", Comptes Rendus Biologies, 2011, p. 599–606 (original not read by us) en.wikipedia.org
- Wikipedia, "Sexual reproduction" (CC BY-SA 4.0), which cites: "DNA Is Constantly Changing through the Process of Recombination", Nature, 2014 (original not read by us) en.wikipedia.org
- Vogt, "Large testicles are linked to infidelity", Phys.org, January 29, 2014. facts only, no text reused. phys.org
- Wikipedia, "Sexual reproduction" (CC BY-SA 4.0), which cites: N.J. Butterfield, "Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes", Paleobiology, 2000, p. 386–404; T.M. Gibson, "Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis", Geology, 2018, p. 135–138 (original not read by us) en.wikipedia.org
- Wikipedia, "Sexual reproduction" (CC BY-SA 4.0), which cites: Otto, "Sexual Reproduction and the Evolution of Sex", Scitable, 2014 (original not read by us) en.wikipedia.org
- Wikipedia, "Sexual reproduction" (CC BY-SA 4.0), which cites: Cecie Starr, "Biology: The Unity and Diversity of Life", Cengage Learning, 2013, p. 281; Vogt, "Large testicles are linked to infidelity", Phys.org, January 29, 2014; Agrawal, "Sexual selection and the maintenance of sexual reproduction", Nature, 2001, p. 692–695 (we also read that source) en.wikipedia.org
- "Fern Reproduction", U.S. Forest Service. facts only, no text reused. fs.usda.gov
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Sexual reproduction (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
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