Asexual reproduction - Simple English Wikipedia, the free encyclopedia

Asexual reproduction is reproduction without sex.

In this form of reproduction, a single organism or cell makes a copy of itself. The genes of the original and its copy are the same except for rare mutations. They are clones.

The main process of asexual reproduction is mitosis. This type of reproduction is common among some single-cell organisms such as Amoeba. Many plants also reproduce asexually such as by means of runners. The individual zooids in a particular coral or bryozoan are usually genetically identical. They are formed by asexual reproduction of the first individual to arrive in a place. One whole order of the rotifers, the bdelloid rotifers, has no sexual reproduction.

Many types of living things have a double cycle. At one stage, they have sexual reproduction, and at another they simply multiply by splitting or producing eggs that develop without being fertilized (aphids). All daughters of the honey bee develop from unfertilized eggs. Asexual reproduction is therefore common in many forms of life.[1][2]

Binary fission

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A cell splitting and becoming two cells (overview)

Some organisms like bacteria reproduce using binary fission. They split into two, and one bacterium becomes two bacteria. That always leads to daughter cells, and the offspring is identical to the parent.

Some plants reproduce by asexual budding; small complete plants grow along the edge of this leaf.

Budding is similar to binary fission but is used by plants and some animals, which cannot simply split into two the way that bacteria can. In budding, a small part of a plant or animal breaks off, and while they are separated from their "mother", they start to grow until both the "parent" and the "offspring" are the same size and are capable of budding again. That may happen many more times.

Parthenogenesis

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Parthenogenesis is found in both plants and animals. Eggs develop without fertilisation. Examples occur in water fleas, rotifers, aphids, stick insects, some ants, bees and parasitic wasps. Parthenogenesis is very rare for vertebrates.[3]

Vegetative propagation

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Vegitative popogation is very common in some types of plants using rhizomes or stolons (such as strawberries). Other plants form bulbs or tubers (for example tulip bulbs and dahlia tubers). Some plants may form a clonal colony, where all the individuals are clones, which may cover a large area.

Asexual reproduction in Ascomycota is by the formation of conidia, a type of spore. Here is a chain of four conidia of Alternaria

Fungi (such as mushrooms) produce spores, which may be asexual or sexual. The asexual spores have the genetic material inside, which allows them to make a whole new organism identical to its parent. The spores are produced by mitosis. Different fungi make different kinds of asexual spores, conidia, oidia, and pycniospores. The shape and the colour of the spores can be helpful to identify the species.

Sexual vs asexual reproduction

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Type Advantages Disadvantages
Asexual reproduction No mate needed. Many offspring produced quickly No variation in the offspring.
Sexual reproduction Genetic variation in the offspring. Requires both sexes to participate.

References

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  1. Dawson K.J. (1995). "The advantage of asexual reproduction: when is it two-fold?". Journal of Theoretical Biology. 176 (3): 341–347. Bibcode:1995JThBi.176..341D. doi:10.1006/jtbi.1995.0203.
  2. Engelstädter J. (2008). "Constraints on the evolution of asexual reproduction". BioEssays. 30 (11–12): 1138–1150. doi:10.1002/bies.20833. PMID 18937362. S2CID 5357709.
  3. Engl, New; Aquarium. "Two baby Anaconda born in all-female adult exhibit". New England Aquarium. Archived from the original on 2019-06-01. Retrieved 2019-06-01.

Other websites

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