Students studying Biology would have come across the topic of asexual reproduction. Fragmentation is one of the most common forms of asexual reproduction. It is a form of cloning in which one organism is broken into smaller fragments. These fragments can be reassembled into fully grown organisms.
Fragmentation is also known as splitting methods of reproduction. It can be seen in many organisms like cyanobacteria and fungi as well as in animals such as flatworms, sponges and annelids worms.
Definition of Fragmentation
The fragmentation is a type of reproduction, which involve the splitting of organisms into smaller pieces. Each of these pieces can develop into mature and fully grown individuals, which are identical to their ancestors.
- Multicellular organisms are characterized by fragmentation as one of their most important processes.
- It involves dividing organisms into smaller pieces, as the name implies.
- It is a form asexual reproduction.
- This mechanism could be accidental or intentional. It is one its most important characteristics.
- Natural damage, such as damage from predators, can cause fragmentation.
- It could be human-made. These organisms may have specific organs that can easily be shattered or shed.
- Although fragmentation can occur without preparation of an organism, it is important that all fragments are able to regenerate full organisms in order to reproduce properly and function properly.
- Fragmentation, as we have already discussed, is a process that involves splitting. It is also called splitting.
- This way of reproducing is found in many organisms like lichens and many plants. It can also be seen in some annelid worms and sponges.
General Steps of Fragmentation
This is the process of reproduction where small organs or other parts of the parent are separated, and then grow into a fully mature organism. Let’s take Planaria, one flatworm belonging to the phylum Platyhelminthes and the class Rhabditophora. The Figure below shows the steps involved in fragmentation in Planaria.
Advantages of Fragmentation
- Fragmentation has the advantage that it can be done with one parent. Mating between males and females is not required. You can easily complete the entire cycle of reproduction by forming fragments from the parent organism, and then their growth into new identical organisms to their respective dynasties.
- A second advantage to fragmentation is its ability to reproduce in a shorter time.
- Fragmentation, a form of asexual reproduction, is very fast.
- Fragmentation is a fast way to produce offspring. It is thought that this allows for a greater number of organisms to be produced in a shorter period of time, as the chain of reproduction moves from one person to two and then from two to four. Fragmentation allows for a new generation of identical organisms to be created from one parent in less time.
- Another advantage of the process is its ability to occur in any environment and under any climatic conditions.
Disadvantages Fragmentation
Diversity is Hinders
Asexual reproduction could limit the genetic diversity of their descendants because only one parent can pass on their traits and characteristics. This results in the organism’s population being exactly the same. This is a major advantage in sexual reproduction because we can mix genes to create a diverse ecosystem.
It Poses Some Heritage Problems
It would only require one asexual parent to copy genes and chromosomes. This means that any genetic defects or mutations caused by asexual reproduction will still be present in offspring. This could lead to more undesirable mutations, making asexually-produced organisms susceptible to diseases. It could also result in the death of many offspring.
This can lead to an extinct-prone organism.
We can assume that any predator or parasite that evolved to eliminate an asexual organism will also have the same traits and characteristics. Asexual reproduction can result in existence struggle.
It Causes Problems with Population Control
This form of reproduction doesn’t control the rapid increase in population within the organisms. Because there is no competition in evolution, each organism is capable of reproducing, which means that their population can even double each cycle. Scientists have discovered that the process will stop when it reaches an excessive level.
It Leads to Organisms to Not Being Able to Adapt
Organisms can respond to certain things by asexual reproduction. This is passed on to their offspring. Because the offspring are less likely to produce variation, they may become less adaptable to environmental changes and not survive. This is more common during the larval editing phase.
Examples of Fragmentation
As a method of reproduction, fragmentation can be found in animals and plants.
Fragmentation in Fungi
Different types of fungi, such as yeasts, molds, and mushrooms, can show fragmentation. They reproduce by fragmentation using a particular type of structure called hyphae. Each of the branching filaments of a fungus’ mycelium can be described as hyphae. They can easily eliminate it as it is a branch of the parent fungi. They get food and other nutrients from their parent fungi bodies during their life cycle. This helps hyphae grow and mature and eventually becomes ready to fertilize. A piece of hyphae is now free from its parent and enters a growth phase as an independent body. They eventually mature and become hyphae.
Fragmentation in Lichens
Lichen is an organism that has been created from cyanobacteria or algae. It is made up of filaments from multiple species of fungi. The properties of combined lichen are different from those of the individual organisms. There are many types of lichens. Many lichens have specialized structures that are easy to break down and disperse. These structures include mycobiont-hyphae as well as algae(phycobiont). (See soredia, isidia). Larger fragments of the thallus may fall apart when the lichen dries, or due to mechanical disturbances (see section on lichens reproduction).
Fragmentation in Plants
Plant fragmentation is a common method of vegetative reproduction. Many non-woody perennials, trees, shrubs and ferns can form clonal colonies through the production of rhizomes (or stolons) that produce new rooted shoots to increase the colony’s size. Fragmentation occurs when a root shoot is removed from the colony. There are many other natural fragmentation mechanisms.
High-skilled reproductive structures are produced: A few plants can produce plantlets from their leaves that become independent plants. Tolmiea Menziesii, daigremontiana kalanchoe. Others create organs like bulbils or turions.
Parts with a high growth potential are easy to lose: woody plants such as the willow naturally shed twigs. Cladoptosis is the name for this phenomenon. These twigs can become roots that will allow for the establishment of new plants in the right environment. Branch fragments from certain species of cottonwood that are growing along the banks of rivers can often be destroyed by currents. The fragments can be used to root new plants in the right environment. Many cactus plants and other plants have stems that are joined together. A stem segment called a pad can fall off and it can grow new plants. Some plants can root easily when their leaves fall off, e.g. Sedum and Echeveria.
Non-vascular plants such as mosses and liverworts can also show fragmentation. Wind, water and animals often scatter small pieces of moss “strains” or leaves. A moose fragment can become a new plant if it reaches the right environment. Gemmae can also be produced, e.g. in Marchantiapolymorpha’s splash – cups, which are easily broken and distributed.
People use fragmentation to artificially spread various plants. This can be done through layering, divisions, grafting and cutting.
Fragmentation in Animals
Sponges and coral colonies are examples of animals that can naturally reproduce and fragment. This is how many species of flatworms and annelids can be reproduced.
When splitting is caused by specific developmental changes, the terms budding, paratomy, and architomy are used. Architomy is when an animal splits at a specific point. The two pieces that remain are used to regenerate any organs or tissues that have been lost. The splitting does not occur before the development of the tissues that will be lost. Before splitting, the animal might develop furrows. The headless fragment must regenerate the entire head.
Paratomy describes the split as occurring perpendicularly to the anteroposterior axis. In the posterior portion, the split is preceded “regeneration” by the anterior structures. They align their bodies axis (i.e. They develop from head to tail. Budding can be compared to paratomy, except that the axes do not have to be aligned. The new head could grow sideways, or even backward (e.g. Convolutriloba Retrogemma is an acoel flatworm.
Coral
Natural and artificial fragmentation can lead to many types of coral colonies increasing in number. For a variety purposes, coral fragmentation is common in reef aquarium hobby. These include shape control, selling, trading or sharing with other people; regeneration experiments; and minimizing the damage to natural coral reefs. You can fragment both soft and hard corals. Acropora and Montipora, Pocillopora and Euphyllia are some of the most tolerant to fragmentation. Fragmentation is the most common way marine anemones reproduce. Longitudinal Fission is where the original anemone splits through its center. This creates two anemones with equal sizes and basal lacration. Small parts of the animal are taken from their base to form a new anemone.
Echinoderms
This process is often called fissiparity among echinoderms, although it is rarely used to refer to fission generally. This method can be used to deliberately reproduce some species.
Asexual reproduction has many advantages. To get the best out of this process, it is important to understand both sides. This knowledge will come in handy if you ever need it.
References
- https://www.toppr.com/ask/content/concept/fragmentation-201509/
- https://unacademy.com/lesson/fragmentation-asexual-reproduction-in-hindi/02N2IVM6
- https://www.vedantu.com/biology/fragmentation
- https://en.wikipedia.org/wiki/Fragmentation_(reproduction)#:~:text=Fragmentation%20in%20multicellular%20or%20colonial,clones%20of%20the%20original%20organism.
- https://www.biologyonline.com/dictionary/fragmentation
