Asexual Reproduction – Types, Advantages and Disadvantages

Reproduction is a biological process that an organism engages in. One of the essential properties of a living entity is its ability to reproduce. Sexual and Asexual reproduction are the two main ways of reproduction. Asexual reproduction is a type of reproduction in which a single parent produces a new offspring. The new individuals produced are genetically and physically similar. 

Both multicellular and unicellular species exhibit asexual reproduction. This reproduction takes place in both natural and artificial ways. Because male and female gametes are not mixed, asexual reproduction generates genetically identical plants to the parent plant. Let us learn more about the types of asexual reproduction with examples. 

What is Reproduction?

Reproduction is the process in which an organism produces a new offspring or individual of its own kind. This is of two types:

1. Asexual reproduction
2. Sexual reproduction

What is Asexual Reproduction?

Asexual reproduction is a type of reproduction that involves the production of offspring by a single parent without involving the formation and fusion of gametes, meiosis, fertilization, transfer of genetic material between two individuals.

Asexual Reproduction in Animals

Asexual reproduction in animals occurs in different ways in different organisms. The different modes or types of asexual reproduction in animals include fission, budding, spore formation, regeneration, and fragmentation.

Fission

It is a type of asexual reproduction in which unicellular organisms divide into two or more than two, small, nearly equal-sized daughter individuals.

It is of two types:

Binary Fission

It refers to the division of the parent cell into two small, nearly equal-sized daughter individuals. Example: Binary fission in Bacteria.

Multiple Fission

The division of a parent cell into many small daughter cells simultaneously is called multiple fission. Under unfavourable conditions, the cyst is formed around the organism’s cell. Under this condition, the parent nuclei divide along with the division of the cytoplasm and produce multiple daughter cells.
Example: Multiple fission in Amoeba.

Budding

A new individual arises on the parent organism as a bud outgrowth. The nucleus of the body divides into two and one of the nuclei pass into the bud. The bud grows and develops and then detaches from the parent cell to become a new individual.
Example: Budding in Yeast.

Learn About Reproduction In Organisms

Spore formation

In this method of asexual reproduction, a small body called spores is formed. Usually, this is seen in kingdom fungi and some algae. These are covered by the hard protective coat that protects the cell from unfavourable conditions such as high temperature, drought, etc. These spores germinate to form a new individual whenever favourable environmental conditions are available. 
Example: Spore formation of Rhizopus.

Fragmentation

In some organisms such as algae – Spirogyra, the filaments break up into two or more fragments upon maturation. These fragments grow into a new individual.
Example: Fragmentation of Spirogyra.

Regeneration

It is a type of asexual reproduction. If a body of the organism undergoes any cut or any wound of any part, that damaged part will regrow, or a new individual will be regenerated from that cut body part. The specialized cells present in the organism can differentiate and grow into a new individual.
Example: Regeneration in Planaria.

Asexual Reproduction in Plants

Plants reproduce asexually in many different ways. Some plants reproduce by spore formation (Ferns and mosses), which is also seen in animals. We will discuss a special mode of asexual reproduction in plants’ vegetative propagation.

What is Vegetative Propagation?

The production of new plants from different vegetative parts of the plant body such as roots, stems, bulbs, leaves, tubers, etc., is called vegetative propagation.

It is of two types:

1. Natural method of vegetative propagation.
2. Artificial method of vegetative propagation.

Natural Method of Vegetative Propagation

Plants propagate naturally through roots, underground stem, creeping stem, aerial stem, leaves, etc. Some natural methods of vegetative propagation are as follows:

Rhizome 

A rhizome is an underground stem that grows horizontally through the soil. It is thick and fleshy since it stores reserved food materials. It has nodes, internodes, scaly left, axillary buds, terminal buds and adventitious roots. The axillary buds later grow into aerial shoots.
Example: Ginger

Corm

A corm is a short stem, swollen with stored food. The corms separate from each other and form new plants.
Example: Gladiolus

Tuber

A tuber is an underground stem that is swollen with a supply of stored food. Stem tubers have several small buds called eyes. These buds obtain their food from the tuber as they grow into a new shoot. The new shoots then develop their tubers.
Example: Potato

Bulb

It is vertical in direction and its terminal buds give rise to the floral shoots. Axillary buds that may be produced in the axils of fleshy scales, grow into aerial shoots under favourable conditions.
Example: Onion

Vegetative Reproduction by Leaves

In some plants, new plants arise at the margins of their leaves in the form of buds. Each bud on separation gives rise to a new plant.
Example: Bryophyllum

Vegetative Propagation by Roots

In plants like sweet potato, the tuberous roots give rise to adventitious buds where new plants arise from it. 

Vegetative Propagation by the Creeping Stem

The stem which creeps on the soil and also on the water surface is called the creeping stem. There are three types:

1. Runners (Oxalis)
2. Stolen (Strawberry)
3. Offset (Eichhornia)

Artificial methods of Vegetative Propagation

It is the method developed by man to develop the horticultural and commercial production of crops. It is a type where many plants are propagated at a very fast rate. The major artificial methods are cutting, grafting, layering and tissue culture.

Cutting

In this method, a piece of a suitable stem length is taken from the mother plant. This cutting having nodes and internodes is placed in moist soil. Roots emerge from the basal portion, and the bud gives rise to shoot. 
Example: Rose

Layering

Layering is the development of roots on a stem while still attached to the parent plant. A layer is called the stem or branch that develops adventitious roots while still attached to the parent plant.
Example: Jasmine

Grafting

Grafting is the method where two parts of the two different plants are joined so that they grow into a single plant. Grafting is done between the closely related dicotyledonous plants having vascular cambium. The rooted supporting portion of one plant is called stock, and the supporting stem portion of another plant is called the scion. These two portions, called scion, are joined together to form a single plant with selected desired characteristics from both the plants. 
Example: The scion of high-quality roses is grafted on wild rose rootstock.

Tissue culture

Tissue culture is a method of propagation of plants by culturing the cells, tissues and organs. This method is also known as micropropagation. The culturing of cells or tissue or organs results in the formation of an undifferentiated mass of cells called callus, which later differentiates to produce many plantlets. These plantlets are then transferred to separate pots or nursery beds to obtain plants.

Advantages of Asexual Reproduction

The advantages of asexual reproduction are as follows:

1. A single parent is required.
2. Requires less energy to reproduce.
3. Each offspring is a genetic copy of the parent.
4. Less likely to become extinct as all organisms are capable of reproduction.
5. Rapid population growth is seen if there is a proper environmental condition.
6. Reproduction is completed much faster than sexual reproduction.
7. The plants raised by vegetative propagation bear flowers and fruits earlier than those produced from seeds.
8. Seedless plants can be produced by vegetative propagation.

Disadvantages of Asexual Reproduction

The disadvantages of asexual reproduction are as follows:

1. It does not lead to genetic variation in a population.
2. An organism born through asexual reproduction only has DNA from one parent. 
3. The disease is likely to affect the whole population as there is no genetic variation.
4. The products of vegetatively propagated plants cannot be stored for long.
5. Due to the absence of variations, asexually reproduced organisms cannot to adapt themselves to change in the environment.

Summary

Every living organism reproduces to continue its generation. From this article, we can conclude that a single parent can produce many individuals, which is advantageous as the asexual reproduction cycle is rapid compared to sexual reproduction. Vegetative reproduction is an ideal way to propagate a greater number of plants.

FAQs

Q.1. What are 3 asexual reproduction examples?
Ans: The three asexual reproduction examples are budding, fragmentation and fission.  

Q.2. What is asexual reproduction and give one example?
Ans: Asexual reproduction is a type where a single parent is involved in the production of offspring. For example, in yeast, the parent cell produces a small bud on its outer surface. This bud develops into a new yeast by detaching itself from its parent cell.

Q.3. What is fission in asexual reproduction?
Ans: Fission is a type of asexual reproduction in which unicellular organisms divide into two or more than two, small, nearly equal-sized daughter individuals. It involves binary fission and multiple fission.

Q.4. Name some plants that reproduce asexually.
Ans: The plants that reproduce asexually are potato, onion, rose, ginger, etc. 

Q.5. What are the two advantages of asexual reproduction?
Ans: The two advantages of asexual reproduction are:
1. A single parent is required.
2. Seedless plants can be produced by vegetative propagation.