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Asexual Reproduction – Definition, Characteristics, Types, Examples

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Asexual Reproduction is a form of reproduction that doesn’t include the fusing of gametes or an increase or decrease in the number of chromosomes. The newly created individual is genetically and physically similar to the parent or an exact clone of the parent when offspring are produced through asexual reproduction from either unicellular or multicellular organisms.

What is Asexual Reproduction?

Asexual reproduction is a type of reproduction where an organism can produce offspring without the involvement of a mate or another organism. In asexual reproduction, the offspring are genetically identical to the parent, as there is no exchange of genetic material between individuals. Asexual reproduction is normally seen in unicellular organisms. Only a single parent is divided into 2 clone cells known as daughter cells. 

Characteristics of Asexual Reproduction in Animals

Following are some of the characteristics of asexual reproduction in animals:

  • No gamete production or fertilization.
  • A single parent is involved, i.e. mother cell.
  • It takes comparatively less time than sexual reproduction.
  • No variety, the children generated are the replicas/clones of the parent.
  • Offspring develops at a very high rate.

Types of Asexual Reproduction

Asexual reproduction can occur in a variety of ways. Fission, fragmentation, and budding are seen in microorganisms like amoeba, hydra, and worms. Vegetative propagation and spore development are observed in plants, algae, and fungi.

Binary Fission

In Binary Fission, a parent cell splits into two or more individuals of almost equal size which are identical to the mother cell each of them having a nucleus and equal genetic material. Examples are bacteria, archaebacteria, unicellular eukaryotes like protists, and some fungi.  

Binary Fission

 

Fragmentation

In Fragmentation, the body is divided into many fragments, which eventually evolve into whole creatures. Examples: Planaria, Worms, Fungi, Plants, and Starfish.

Fragmentation in Planaria

Budding

In budding, a bud-like outgrowth develops on the parent body, which is similar to the parent organism. Organisms reproduce by splitting off new individuals from existing ones through budding and resulting in genetically identical parent and daughter organisms. The bud may remain linked, or it may break loose through the parent. Budding generally occurs in eukaryotic species such as single-celled yeast and multicellular Hydra.

Budding

Budding In Hydra

Vegetative Propagation

In plants, Asexual reproduction occurs through their vegetative parts such as leaves, roots, stems, and buds, this type of reproduction is called vegetative propagation. For example, runners/stolon, potato tubers, onion bulbs, etc. shows vegetative propagation.

Grafting

Grafting, type of Vegetative Propagation

Spore Formation

Spore formation is one of the types of asexual reproduction in plants. In harsh or unfavorable conditions, the organism develops ball-like sac structures called sporangium that contain spores. In favorable conditions, the sporangium burst open (air/water), and spores are released into the surrounding that germinates to give rise to the new organisms. Example fungus-like Bread Mould.

Spore Formation

Asexual Reproduction in Plants

Plants frequently reproduce by asexual reproduction. The money needed to grow a flower, entice pollinators, or develop a way to spread seeds is not needed with this strategy. The resultant plants are genetically identical to the parent plant because asexual reproduction prevents the mixing of male and female gametes. These plants often outperform plants produced through sexual reproduction in stable environmental conditions because they share the same DNA as their parents.

The two main asexual reproductive processes in plants are vegetative reproduction and apomixis. New plant individuals are created by vegetative reproduction rather than through the creation of seeds or spores. Vegetative reproduction is exhibited by a wide variety of roots. Garlic and gladiolus both use the corm.

Asexual Reproduction in Animals

Animals can reproduce asexually, which is when just one parent produces offspring. This type of reproduction is typically seen in single-celled organisms. Here, a single parent cell splits into two or more daughter cells without any gametic fusion taking place. Clones are the resultant children that are both genetically and physically identical to their parents. There are many methods in which asexual reproduction can take place. The following are some examples of asexual reproduction in animals:

Budding

In budding, children grow on the parent’s body as a growth. In other species, such as jellyfish and many echinoderms, the buds separate and live on their own. In others, like corals, the procedure results in animal colonies because the buds stay joined to the parent. Budding is also typical of animals that are parasites, such as tapeworms.

Fragmentation

Some microscopic worms spontaneously split into 8 or 9 parts as they reach their maximum size. These fragments all develop into full-grown worms, and the cycle is again repeated.

Parthenogenesis

Females produce eggs during parthenogenesis (“virgin birth”), but the eggs never fertilize and develop into offspring. Some fish species, various types of insects, and a few frog and lizard species all engage in parthenogenesis. Due to their imprinted genes, mammals typically do not experience it. However, laboratory mice have been created by parthenogenesis using specific modifications to avoid imprinting.

Asexual Reproduction in Humans

Humans normally reproduce through sexual reproduction since they are complex organisms. The child receives one-half of one pair of chromosomes from the mother and the other half from the father. The two gametes must fuse in order for fertilization and implantation in the female reproductive system to occur. As a result, both of the parents’ traits are passed down to the children.

Humans occasionally reproduce asexually as well. It happens without the gametes being fertilized pertaining to monozygotic twins. In this, the egg is sexually fertilized, and the embryo is produced, but the embryo divides into two through an asexual process. The artificial technique used in the invitro mode of reproduction is another way that humans can reproduce asexually. The egg and sperm are joined in this small portion of the sperm, where the egg develops and matures into the new baby.

Advantages of Asexual Reproduction

The following are the advantages of asexual reproduction:

  • Mates/partners are not required.
  • The reproduction process is fast.
  • Numerous organisms can be produced in a short time.
  • Positive genetic influences are passed on to successive generations.
  • It occurs in all kinds of environments.

Disadvantages of Asexual Reproduction

The major disadvantages of asexual reproduction are:

  • As the offspring are genetically identical to their parent, the diseases or nutrient deficiency is passed on to the next generation.
  • The diversity among the organisms is limited as only one organism is involved.
  • Offsprings are unable to adapt to new environments.
  • A single change in the environment would result in the elimination of the entire species.

Examples of Asexual Reproduction

Some of the examples of asexual reproduction are:

  • Bacterium shows binary fission.
  • In starfish, worms reproduce through the fragmentation method.
  • Hydras reproduce via budding.
  • Sugarcane is cultivated using the vegetative propagation method.
  • Succulent plants are grown and re-grown using the plant part, which is the form of vegetative reproduction.
  • Through vegetative propagation, sugarcane can be grown.

FAQs on Asexual Reproduction

1. What is Asexual Reproduction?

Answer:

Asexual reproduction is a type of reproduction in which a single parent cell is involved in making a new offspring. Any kind of sexual gametic fusion between male and female gamete is not involved, and the number of chromosomes remains the same as the mother cell.

2. What are the types of Asexual Reproduction?

Answer:

Asexual reproduction takes many different forms. There are three main types:

  • Binary fission: A single parent cell divides into two cells after doubling its DNA. occurs frequently in bacteria.
  • Budding: Two new individuals are created when a little growth on the parent’s surface breaks off. Occurs in some animals such as the hydra and yeast.
  • Fragmentation: Organisms can split into two or more fragments, each of which can grow into a distinct individual.

3. What is the importance of Asexual Reproduction?

Answer:

Asexual reproduction can be beneficial or harmful. One advantage is that it can produce people quickly and in great numbers. Secondly, since motile sperm need water to fertilize the egg, avoiding the sexual process can be beneficial to a plant during dry periods.

4. Can humans reproduce asexually?

Answer:

Humans do not experience parthenogenesis. However, lizards have been known to exhibit it. Cloning, which obviously involves medical assistance, is an asexual reproduction. Humans cannot reproduce asexually when left on their own.

5. Are frogs asexual?

Answer:

Every frog reproduces sexually and emerges from an egg. Almost all frogs undergo external rather than internal egg fertilization. Both the male and female release their sperm and eggs simultaneously.



Last Updated : 08 Sep, 2023
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