Reproduction, in which one or more cells are separated from part of the mother’s body, is called asexual. In this case, for the appearance of offspring, one parent is enough.
Types of Asexual Reproduction
In nature, there are several options for how living organisms can reproduce their own kind. Methods of asexual reproduction are quite diverse. All of them consist in the fact that cells begin to divide and reproduce daughter individuals. In unicellular protozoa, the whole organism is divided into two parts. In multicellular reproduction begins with the division of one or more cells simultaneously.
The simplest organisms, plants, fungi, and some animal species are characterized by asexual reproduction. Reproduction methods can be as follows: division, spore formation. Separately note the appearance of offspring, in which it is formed from a group of cells of the mother. They are called vegetative propagation. Separate budding, fragmentation. These are common methods of asexual reproduction. The table provides an opportunity to understand how they differ.
Breeding method | Features | Organisms |
division | The cell is divided into 2 parts, forming 2 new individuals | Blue-green algae, bacteria, protozoa |
Spore formation | In special sections of the body (sparging) spores are formed | Some plants, fungi, some protozoa |
Vegetative | A daughter organism is formed from several cells of the parent | Annelid worms, intestinal organisms, plants |
Features of the simplest reproduction
In all organisms that are capable of producing offspring by division, the ring chromosome is pre-doubled. The core is divided into two parts. From one parent cell, two daughter cells are formed. Each of them contains identical genetic material. Between the two daughter cells formed, a constriction appears along which the parent is divided into two cells. This is the simplest asexual reproduction.
Reproduction methods may be different. But euglens green, chlamydomonas, amoeba, ciliates use precisely division. The resulting offspring is no different from parental individuals. He has exactly the same set of chromosomes. This method of reproduction allows you to quickly get a large number of identical organisms.
Spore formation
Some fungi and plants reproduce using special haploid cells. They are called disputes. In many fungi and lower plants, these cells are formed during mitosis. And in higher plant organisms, their formation is preceded by meiosis. A feature of this process is that the spores of such plants contain a haploid set of chromosomes. They are able to give rise to a new generation that is different from the mother. It can reproduce already sexually. At the same time, do not forget for their unique feature. Methods of sexual and asexual reproduction in such plants alternate.
In most fungi and plants, the formed spores are cells that are protected by special shells. They can be stored for a while under adverse conditions. When they change, the membranes open, and the cell begins to actively divide by mitosis. As a result, a new organism is formed.
Vegetative self-reproduction
Most higher plants use other methods of asexual reproduction. The table allows you to understand what types of vegetative reproduction exist.
Vegetative propagation method | Features |
Branch of roots, cuttings, bulbs, mustaches, tubers, rhizomes | Reproduction requires a well-formed part of the mother’s body, from which the daughter will begin to develop |
Fragmentation | The parent individual is divided into several parts, from each a separate independent organism develops |
Budding | A kidney is formed on the parent body, from which a new full-fledged organism is formed |
During vegetative propagation, special structures can form in plants. For example, potatoes and dahlias create offspring of tubers. So called root or stem thickenings. The swollen base of the stem from which the offspring is formed is called corm.
Rhizomes propagate plants such as aster and valerian. Also called horizontally growing underground stems from which buds and leaves appear.
Strawberries, strawberries form offspring with the help of a mustache. They grow quickly enough, from them new leaves and buds appear. All these methods of asexual reproduction of organisms are called vegetative. They also include reproduction using cuttings of stems, roots, and part of thalli.
Fragmentation
This type of reproduction is characterized by the fact that when the maternal organism is divided into several parts, a new individual is formed from each of them. Some ringed and flatworms, echinoderms (starfish) use such asexual reproduction. Methods of propagation by fragmentation are based on the fact that some organisms can be restored by regeneration.
For example, if a ray is torn from a starfish, a new individual will be formed from it. The same thing will happen with the earthworm, divided into several parts. Hydra, by the way, can recover from 1/200 of the part separated from its body. Usually such reproduction is observed in case of damage. Spontaneous fragmentation is observed in molds and some marine worms.
Budding
Asexual reproduction methods allow reproduction of exact copies of parental organisms. In some cases, daughter individuals are formed from special cells - the kidneys. This method of self-reproduction is characteristic of some fungi, animals (sponges, protozoa, intestinal, a number of worms, winged-winged individuals, tunicates), and liver mosses.
For intestinal, for example, such asexual reproduction is characteristic. Their reproduction methods are quite curious. An outgrowth appears on the body of the maternal individual, which increases. As soon as it reaches the size of an adult, its separation occurs.