Fragmentation is a type of asexual reproduction that can be defined as breaking down of organism or part of an organism into many smaller fragments, each fragment can develop into mature organisms or fully grown individuals similar to their parents.
Fully grown individuals are similar to ancestors concerning shape, size, genome, and dimension.
The fragmentation process is the most important mechanism in multicellular organisms (made up of multiple cells) to produce offspring.
The most important characteristic of fragmentation is that the process can occur both unintentionally (environmental changes may cause the fragmentation) and intentionally (man causes to fulfill different purposes).
Both animals and plants are reproduced by fragmentations, seen in many organisms such as fungi, lichens, worms, molds, sea stars, sponges, flatworms, Cyanobacteria, etc.
In a fragmentation process, a single parent is involved to produce offspring, this process is relatively faster than other reproductive processes, and genetic variation is absent in the next generation.
Sometimes fragmentation is confused with regeneration, but these processes are not interchangeable. Fragmentation is a splitting method that produces offspring of organisms, whereas regeneration occurs when an organism only grows a lost part of the body (example: the tail of a lizard).
Two fragmentation methods are mainly seen in an organism; paratomy and achitomy.
In paratomy, the organism splits perpendicular to the anterior to the posterior axis, and in achitomy regrow of the missing organ(part) and tissue occurs from the point of fragmentation.
Fragmentation in plants
- Fragmentation is a common type of vegetative reproduction in the plant.
- Most trees, shrubs, fern, non-woody, and perennials produced clonal colonies via producing rhizomes or stolons to produce new rooted shoots that increase the colony diameter.
- If a root detached from the colony, it grows on its own new root system.
Example: Willows trees (woody plants) can be reproduced (growing new plants) under appropriate environmental conditions through their roots on the ground. This natural shedding of branches is known as cladoptosis.
- Some plants and cactus have stem joined together that can root and produce new plant when a stem segment called a pad, fall off.
- Fragmentation is also seen in non-vascular plants, for example, liver worth and mosses.
- Leaves or strains of moss are dispersed from water or animals and wind into small pieces called a fragment. In an appropriate environment, these fragments can complete the growth cycle and produce a new plant.
- People have utilized the fragmentation process for artificially spreading various plants. This is done by division, grafting, layering, micropropagation, and cutting.
Fragmentation in animals
- In animals, fragmentation is found in many coral colonies. Both types of coral (soft coral and hard coral) are easily fragmented, and many marine anemones grow themselves by the splitting process.
- Breeds such as Montipora, Acropora, Pocillopora, Euphyllia, and Caulastrea are also capable of fragmentation.
- The most common example of animal fragmentation is starfish and planaria.
- Some of the sea stars reproduce a new individual from a broken arm and a piece of the central disc.
- Planaria is a flatworm, included in the class of Rhabditophora and phylum Platyhelminthes. During the fragmentation process, the body of an organism is split into small fragments or organs. In an appropriate environment, these fragments start to grow and become mature or new individuals after the growth cycle is complete.
Fragmentation in fungi
- Hyphae is achieved through the process of splitting, which are the branches of the parent fungi from where they can be easily detached and transform themselves.
- Fragment of hyphae can produce new colonies by fragmentation process.
- The septate hyphae split into their component cell, and each fragment may grow into a new individual.
- They are known as Oidium or arthrospore.
- They do not store reserve food and hence cannot survive under unfavorable conditions. example: Erysiphe, Rhizopus
- Mycelium fragmentation starts with the separation of fungal mycelium into small pieces. These grow and produce new mycelium that is similar to parent mycelium.
Fragmentation in algae
- In algae, the filamentous thallus split into pieces called a fragment. Each fragment can form or produce a new thallus.
- Fragmentation occurs due to insect bites, mechanical pressure, etc.
- The most common examples are spirogyra, Ulothrix, Oedogonium, Zygnema, Oscicillatoria, etc.
- Spirogyra achieved vegetative reproduction by fragmentation. A vegetative filament of spirogyra breaks down into several small pieces. These fragments undergo multiple divisions and elongate to produce a new filament.
- Algae split into fragments because of the dissolution of the middle lamella as the water temperature and salinity vary or due to mechanical injury.
- The filament may be split when one cell, central lamella, protrudes into an adjacent cell.
- Fragmentation paly a major role in the reproduction of an organism.
- DNA fragmentation technique helps in DNA cloning via recombinant DNA technology (by cleaving and cloning specific DNA fragments from an organism’s genome).
- Fragmentation also occurs in a cellular process called apoptosis.
- A single parent produces many offspring. Mating between males and females is not required.
- The formation of new offspring can be achieved in a relatively short time and easily.
- Limited or no genetic variation is observed in the new generation and also identical to parents in terms of shape, size, and dimension.
- Fragmentation plays a vital role in biology in its ability to occur and progress in any environment and any climate condition and in maintaining equilibrium in the ecosystem via forming larger organisms in a relatively short time.
- To increase the production of plants artificially, fragmentation can also be used.
- Genetic diversity is not produced in the offspring, so these are more vulnerable to changing environments.
- Same heritage problem, traits, chromosomes present in the parents transform into the new generation. In conclusion, due to some of the diseases which they inherited, the offspring may be subjected to early extension.
- A small change in the environment may be eliminated the entire species.
- Identical offspring produced by fragmentation such offspring bodies are weak and have the low capability to defend themselves from predators and parasitic attacks.
- As it is a chain process, i.e, an organism divides into two, and those two further divides into two, this leads to the reproduction of a massive population from a single parent this creates various problem in a control population.