Skip to main content
Select Source:

asexual reproduction

asexual reproduction Reproduction in which new individuals are produced from a single parent without the formation of gametes. It occurs chiefly in lower animals, microorganisms, and plants. In microorganisms and lower animals the chief methods are fission (e.g. in protoctists), fragmentation (e.g. in some aquatic annelid worms), and budding (e.g. in cnidarians and yeasts). The principal methods of asexual reproduction in plants are by vegetative propagation (e.g. bulbs, corms, tubers) and by the formation of spores. Spore formation occurs in mosses, ferns, and other plants showing alternation of generations, as a dormant stage between sporophyte and gametophyte, and in some algae and fungi, to produce replicas of the organism. Compare sexual reproduction.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"asexual reproduction." A Dictionary of Biology. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"asexual reproduction." A Dictionary of Biology. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/asexual-reproduction-1

"asexual reproduction." A Dictionary of Biology. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/asexual-reproduction-1

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Reproduction, Asexual

Reproduction, Asexual

Although sexual reproduction is more frequent, asexual reproduction also commonly occurs in the plant kingdom. The technical term for asexual reproduction in plants is apomixis, derived from apo meaning "without," and mixis meaning "mingling." Apomixis thus refers to the fact that asexual reproduction lacks the mixing of genes that occurs in sexual reproduction. In apomixis, a new individual is produced by a single parent without pollination or mixing genetic material. A familiar example of apomixis is the production of new plants by the growth of horizontal stems (runners) in strawberries (genus Fragaria ). Other familiar plants with asexual reproduction include blackberries (genus Rubus ) and dandelions (genus Taraxacum ), both of which produce asexually formed seeds. Apomixis is of great interest to plant breeders, because it allows the production of exact genetic duplicates of plants with favorable characteristics.

Asexual reproduction in plants is divided into two general types: vegetative reproduction and agamospermy. Vegetative reproduction refers to the formation of new plants by the growth of specialized structures that can survive after physical separation from the parent. Examples include growth by above- or below-ground stems (called stolons and rhizomes), and layering, in which the stem of a woody plant forms roots upon contact with the soil. Fragments of some plants can also grow to form new individuals. Poplar trees (genus Populus ), for example, often shed branches that become rooted and produce new trees below the parent. Poplar trees can be easily propagated by simply cutting off branches and planting them directly in the ground.

Asexual reproduction by seed, called agamospermy, occurs when a single parent plant forms seeds without pollination. Agamospermy thus differs from self-pollination, in which pollen produced by a plant fertilizes its own ovules. Asexually produced seeds also differ in their development from typical, sexually produced seeds. In some plants, maternal diploid cells (which, in a normal seed, do not contribute to the new embryo) divide via mitosis and overgrow the developing ovule. The seed produced is thus genetically identical to the parent plant. A number of tropical fruit trees, such as mangos (Mangifera spp.), can reproduce in this manner.

Asexual reproduction is thought to be an important adaptation for plants that colonize open areas and harsh environments and, as such, is perhaps most common in plant species in arctic and alpine environments. The advantage may be that an asexually reproducing individual reaching a new area can always reproduce, even if no other plants of that species are present. Asexual reproduction also means that a plant's offspring will share 100 percent of its genes, while sexually produced offspring share only 50 percent of their genes with each parent. Evolutionary theorists have argued that, all other things being equal, this should act to favor asexual reproduction, since a parent thereby guarantees that all of its genes are represented in the next generation.

The main disadvantage of asexual reproduction is lack of genetic variation. For example, a disease or pest that has a large effect on one individual may be able to quickly infect all other individuals that share the same exact genetic makeup. In the long run, asexual reproduction may often be an evolutionary dead-end because plants that only reproduce asexually cannot recombine genes to produce new genetic variants.

see also Propogation; Reproduction, Sexual; Stems; Tissue Culture.

Sean C. Thomas

Bibliography

Raven, Peter. H., Ray F. Evert, and Susan E. Eichhorn. Biology of Plants, 6th ed. New York: W. H. Freeman and Co., 1999.

Richards, A. J. Plant Breeding Systems, 2nd ed. London: Chapman & Hall, 1997.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Reproduction, Asexual." Plant Sciences. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"Reproduction, Asexual." Plant Sciences. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/science/news-wires-white-papers-and-books/reproduction-asexual

"Reproduction, Asexual." Plant Sciences. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/news-wires-white-papers-and-books/reproduction-asexual

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

asexual

a·sex·u·al / āˈsekshoōəl/ • adj. without sex or sexuality, in particular: ∎  Biol. (of reproduction) not involving the fusion of gametes. ∎  Biol. without sex or sexual organs: asexual parasites. ∎  without sexual feelings or associations. DERIVATIVES: a·sex·u·al·i·ty / āsekshoōˈalitē/ n. a·sex·u·al·ly adv.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"asexual." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"asexual." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/asexual-0

"asexual." The Oxford Pocket Dictionary of Current English. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/asexual-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

asexual reproduction

asexual reproduction Reproduction without the sexual processes of gamete formation. It occurs by fission in many protozoan animals but also in some multicellular ones (e.g. corals); by budding (gemmation) in many coelenterates and sea squirts (Urochordata); and by parthenogenesis in some vertebrates (e.g. lizards).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"asexual reproduction." A Dictionary of Zoology. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"asexual reproduction." A Dictionary of Zoology. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/asexual-reproduction-0

"asexual reproduction." A Dictionary of Zoology. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/asexual-reproduction-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

asexual reproduction

asexual reproduction Type of reproduction in organisms that does not involve the union of male and female reproductive cells (gametes). It occurs in several forms: fission (division), budding and vegetative reproduction. See also clone; sexual reproduction

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"asexual reproduction." World Encyclopedia. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"asexual reproduction." World Encyclopedia. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/asexual-reproduction

"asexual reproduction." World Encyclopedia. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/asexual-reproduction

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

asexual reproduction

asexual reproduction A type of reproduction without the sexual processes of gamete formation. In plants it consists of vegetative reproduction, apospory, and apogamy. It occurs by budding (gemmation) in many liverworts and mosses. See also APOMIXIS.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"asexual reproduction." A Dictionary of Plant Sciences. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"asexual reproduction." A Dictionary of Plant Sciences. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/asexual-reproduction

"asexual reproduction." A Dictionary of Plant Sciences. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/asexual-reproduction

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

asexual

asexualdenial, dial, espial, Lyall, mistrial, myall, Niall, phial, trial, vial, viol •sundial •knawel, withdrawal •avowal, Baden-Powell, bowel, disembowel, dowel, Howell, Powell, rowel, towel, trowel, vowel •semivowel •bestowal, koel, Lowell, Noel •loyal, royal, viceroyal •accrual, construal, crewel, cruel, dual, duel, fuel, gruel, jewel, newel, renewal, reviewal •eschewal •artefactual (US artifactual), contractual, factual, tactual •perpetual •aspectual, effectual, intellectual •conceptual, perceptual •contextual, textual •habitual, ritual •conflictual • instinctual • spiritual •mutual • punctual • virtual • casual •audio-visual, televisual, visual •usual • gradual • individual •menstrual • actual •asexual, bisexual, heterosexual, homosexual, psychosexual, sexual, transsexual, unisexual •accentual, conventual, eventual •Samuel •annual, biannual, Emanuel, Emmanuel, manual •Lemuel •consensual, sensual •continual

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"asexual." Oxford Dictionary of Rhymes. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"asexual." Oxford Dictionary of Rhymes. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/asexual

"asexual." Oxford Dictionary of Rhymes. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/asexual

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Asexual reproduction

Asexual reproduction

Resources

Sexual reproduction involves the production of new cells by the fusion of sex cells (sperm and ova) to produce a genetically different cell. Asexual reproduction is the production of new cells by simple division of the parent cell into two daughter cells (called binary fission). Since there is no fusion of two different cells, the daughter cells produced by asexual reproduction are genetically identical to the parent cell.

The adaptive advantage of asexual reproduction is that organisms can reproduce rapidly and so colonize favorable environments rapidly.

Bacteria, cyanobacteria, algae, most protozoa, yeast, dandelions, and flatworms all reproduce asexually. When asexual reproduction occurs, the new individuals are called clones, because they are exact duplicates of their parent cells. Mosses reproduce by forming runners that grow horizontally and produce new stalks; the runner then decomposes, leaving a new plant, which is a clone of the original.

A starfish can regenerate and eventually produce a whole new organism from one of its severed appendages.

Duplication of organisms, whether occurring sexually or asexually, involves the partitioning of the genetic material (chromosomes) in the cell nucleus.

KEY TERMS

Binary fission
The process in which cell division occurs and two cells are produced where only one existed before.
Blastomere separation
Cloning by splitting multi-celled embryos.
Gamete
A male or female sex cell capable of reproduction.
Regeneration
The ability of an organism to reproduce wholly from a part of another one.
Replication
The production of new cells like the original one.
Vegetative propagation
A type of asexual reproduction in plants involving production of a new plant from the vegetative structuresstem, leaf, or rootof the parent plant.

During asexual reproduction, the chromosomes divide by mitosis, which results in the exact duplication of the genetic material into the nuclei of the two daughter cells. Sexual reproduction involves the fusion of two gamete cells (the sperm and ova) which each have half the normal number of chromosomes, a result of reduction division known as meiosis.

Bacteria reproducing asexually can double their numbers rapidly; for example, under ideal conditions of nutrients and temperature, Escherichia coli are capable of growth and division in approximately 20 minutes. This reproduction rate is offset by a high death rate, possibly as a result of the accumulation of alcohol or acids that concentrate from the bacterial colonies. Bacteria in other niches, such as infections and in oxygen-poor environments, also reproduce asexually, but at a much slower pace. The time for one bacterium to divide to form two bacteria can be on the order of weeks or even months.

Yeasts reproduce asexually by budding, as well as reproducing sexually. In the budding process, a bulge forms on the outer edge of the yeast cell as nuclear division takes place. One of these nuclei moves into the bud, which eventually breaks off completely from the parent cell. Budding also occurs in flatworms, which divide into two and then regenerate to form two new flatworms.

Bees, ants, wasps, and some other insects can reproduce sexually or asexually. In asexual reproduction, eggs develop without fertilization, a process called parthenogenesis. In some species the eggs may

or may not be fertilized; fertilized eggs produce females, while unfertilized eggs produce males.

There are a number of crop plants that are propagated asexually. The advantage of asexual propagation to farmers is that the crops will be more uniform than those produced from seed. Some plants are difficult to cultivate from seed, and asexual reproduction in these plants makes it possible to produce crops that would otherwise not be available for commercial marketing.

The process of producing plants asexually is called vegetative propagation and is used for such crops as potatoes, bananas, raspberries, pineapples, and some flowering plants used as ornamentals. Farmers plant the eyes of potatoes to produce duplicates of the parent. With banana plants, the suckers that grow from the root of the plant are separated and then planted as new ones. With raspberry bushes, branches are bent and covered with soil. They then grow into separate plants with their own root systems and can eventually be detached from the parent plants.

See also Buds and budding; Clone and cloning; Genetics.

Resources

Ellstrand, Norman C. Dangerous Liaisons?: When Cultivated Plants Mate with their Wild Relatives. Baltimore: The Johns Hopkins University Press, 2003.

Majerus, Michael E. N. Sex Wars: Genes, Bacteria, and Biased Sex Ratios. Princeton: Princeton Univerity Press, 2003.

ONeill, Sherman, and Jeremy A. Roberts. Plant Reproduction. New York: Blackwell, 2001.

Vita Richman

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Asexual reproduction." The Gale Encyclopedia of Science. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"Asexual reproduction." The Gale Encyclopedia of Science. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/asexual-reproduction

"Asexual reproduction." The Gale Encyclopedia of Science. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/asexual-reproduction

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Asexual Reproduction

Asexual reproduction

Sexual reproduction involves the production of new cells by the fusion of sex cells (sperm and ova) to produce a genetically different cell . Asexual reproduction, on the other hand, is the production of new cells by simple division of the parent cell into two daughter cells (called binary fission). Since there is no fusion of two different cells, the daughter cells produced by asexual reproduction are genetically identical to the parent cell.

The adaptive advantage of asexual reproduction is that organisms can reproduce rapidly, and so colonize favorable environments rapidly.


In nature

Bacteria , cyanobacteria, algae , most protozoa , yeast , dandelions, and flatworms all reproduce asexually. When asexual reproduction occurs, the new individuals are called clones, because they are exact duplicates of their parent cells. Mosses reproduce by forming runners that grow horizontally, produce new stalks, and then the runner decomposes, leaving a new plant which is a clone of the original.

Starfish can regenerate and eventually produce a whole new organism from one of its severed appendages.

Duplication of organisms, whether sexually or asexually, involves the partitioning of the genetic material (chromosomes) in the cell nucleus.

During asexual reproduction, the chromosomes divide by mitosis , which results in the exact duplication of the genetic material into the nuclei of the two daughter cells. Sexual reproduction involves the fusion of two gamete cells (the sperm and ova) which each have half the normal number of chromosomes, a result of reduction division known as meiosis .

Bacteria reproducing asexually double their numbers rapidly, approximately every 20 minutes. This reproduction rate is offset by a high death rate that may be the result of the accumulation of alcohol or acids that concentrate from the bacterial colonies.

Yeasts reproduce asexually by budding, as well as reproducing sexually. In the budding process, a bulge forms on the outer edge of the yeast cell as nuclear division takes place. One of these nuclei moves into the bud, which eventually breaks off completely from the parent cell. Budding also occurs in flatworms, which divide into two and then regenerate to form two new flatworms.

Bees , ants , wasps , and other insects can reproduce sexually or asexually. In asexual reproduction, eggs develop without fertilization , a process called parthenogenesis . In some species the eggs may or may not be fertilized; fertilized eggs produce females, while unfertilized eggs produce males.

There are a number of crop plants which are propagated asexually. The advantage of asexual propagation to farmers is that the crops will be more uniform than those produced from seed. Some plants are difficult to cultivate from seed and asexual reproduction in these plants makes it possible to produce crops that would otherwise not be available for commercial marketing.

The process of producing plants asexually is called vegetative propagation and is used for such crops as potatoes, bananas, raspberries, pineapples, and some flowering plants used as ornamentals. Farmers plant the so-called " eyes" of potatoes to produce duplicates of the parent. With banana plants, the suckers that grow from the root of the plant are separated and then planted as new ones. With raspberry bushes, branches are bent and covered with soil . They then grow into a separate plant with their own root system and can eventually be detached from the parent plant.

See also Buds and budding; Clone and cloning; Genetics.


Resources

books

leone, francis. genetics: the mystery and the promise. blueridge summit, pa: tab books, 1992.

taylor, martha. campbell's biology student study guide. redwood city, ca: benjamin/cummings, 1990.

periodicals

allison, richard. "genetic engineering studied." cancer researcher weekly (21 march 1994): 13.

Nash, J. Madeleine. "Is Sex Really Necessary?" Time (20 January 1992): 47.

Robertson, John A. "The Question of Human Cloning." TheHastings Center Report (March/April 1994): 6.


Vita Richman

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Binary fission

—The process in which cell division occurs and two cells are produced where only one existed before.

Blastomere separation

—Cloning by splitting multicelled embryos.

Gamete

—A male or female sex cell capable of reproduction.

Regeneration

—The ability of an organism to reproduce wholly from a part of another one.

Replication

—The production of new cells like the original one.

Vegetative propagation

—A type of asexual reproduction in plants involving production of a new plant from the vegetative structures—stem, leaf, or root—of the parent plant.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Asexual Reproduction." The Gale Encyclopedia of Science. . Encyclopedia.com. 10 Sep. 2018 <http://www.encyclopedia.com>.

"Asexual Reproduction." The Gale Encyclopedia of Science. . Encyclopedia.com. (September 10, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/asexual-reproduction-0

"Asexual Reproduction." The Gale Encyclopedia of Science. . Retrieved September 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/asexual-reproduction-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.