Introduction
Asexual reproduction is one of the two methods of reproduction, the other being sexual reproduction. In asexual reproduction, offsprings or new organisms are developed, often from a single parent, without the fusion of male and female gametes. Therefore, there is no intermixing of hereditary characteristics. As a result, the offsprings produced by asexual reproduction are genetically identical to their parent(s).
Methods of Asexual Reproduction
Fission
The process of reproduction by which a single mother organism splits into two or more daughter organism is called fission.
On the basis of number of offsprings, it is categorized into two types:
- Binary Fission: Fission in which there is the production of only two daughter organisms is called binary fission. Some unicellular organisms like bacteria, euglena, amoeba, paramecium, paslmodium, etc. reproduce by binary fission.
- Multiple Fission: Fission in which there is the production of more than two daughter organisms is called multiple fission. Many unicellular algae and some unicellular animals like the amoeba, plasmodium, etc. reproduce asexually by multiple fission during unfavourable conditions.
Budding
Budding is an asexual method of reproduction, in unicellular plants like the yeast and multicellular animals like the hydra, in which new organisms are produced from the bulb-like projection (bud) arising from the parent’s body.
Sporulation
In sporulation, new organisms develop from the spores of the parent plant. This reproduction is carried out in unfavourable conditions where the spores are dispered out from the sporangia.
Fragmentation or Regeneration
In scientific study, fragmentation is a term used for asexual reproduction in plants and regeneration is used for animals. Fragmentation is the process by which a single mother organism divides into numerous smaller fragments, each capable of developing into a new organism. It is commonly seen in Spirogyra. Regeneration is the ability of an organism to re-gain or re-develop its lost parts. Sometimes, it is capable of regenerating its whole body as well. Reproduction by regeneration is commonly seen in Planaria.
Vegetative propagation
The method of producing new plants with the help of their vegetative parts like roots, stems or leaves is called vegetative propagation. It is a faster method of reproduction in plants.
Natural Methods of Vegetative Propagation
Following activities happen in plants naturally without the invovlement of human efforts.
- Vegetative propagation by roots: In this method, new plants are grown with the help of adventitious buds present in the roots. It is commonly seen in sweet potatio, dahlia, mint, etc.
- Vegetative propagation by stem: Some plants are observed to reproduce asexually with the help of the buds present on their stem. It is commonly observed in onion, rose, potatio, etc.
- Vegetative propagation by leaves: Plants like Begonia, Eucalyptus, etc. reproduce asexually with the help of adventitious buds present on their leaves.