Increasing the number of individuals of their species is the most important task of any organism. That is why along with sexual reproduction, asexual has appeared. Plants, in their own way, have adapted to effective distribution, using the organs of their body for this. What is the biological significance of asexual reproduction? What are the advantages and disadvantages of this method?
What is asexual reproduction?
One of the goals of a living organism is to reproduce its own kind. To solve this problem, plants, animals, bacteria and other representatives of the biological world have found their own ways to increase numbers. It is not in vain that reproduction is referred to one of the parameters of all life along with growth, energy exchange, constancy of the internal environment, etc.
Asexual reproduction is a method in which the participation of germ cells is not required. Gametes play an exceptional role in the formation of new genetic material of the embryo; however, it is not always possible to switch to sexual reproduction. What is the biological significance of asexual reproduction?
For some organisms, such as bacteria, this is the only way to increase population. For the rest of the representatives of the animal and plant world, asexual and sexual reproduction are equally necessary. If the former is used for a quantitative increase in numbers, then the latter is used for a qualitative increase (that is, a change in genetic material).
Types of Asexual Reproduction
Reproduction of their own kind with great speed - that is the biological significance of asexual reproduction of organisms. This type of reproduction is more ancient, and therefore the peak of its dominance falls on low-developed organisms. Next will be presented the types of asexual reproduction that may occur in different taxonomic groups.
- Binary division This type of reproduction is characteristic of most representatives of prokaryotes and protozoa. The cell forms a transverse septum, which divides it in half, thereby forming two daughter cells.
- Schizogony. This method can be considered an improved version of binary division, when several daughter cells develop from one cell at once. The nucleus first divides, and then the cell itself. This type of reproduction can be observed in the life cycle of sporozoans (for example, malarial plasmodium), as well as some algae.
- Budding. Despite the simplicity of binary division and schizogony, not for all organisms these reproduction methods can be effective. For such primitive multicellular animals as Intestinal, budding is characteristic - the formation of a new organism in the form of an outgrowth, which is first connected to the parent individual, and then comes off. If such a "kidney" does not detach, colonies from several organisms are formed. Budding is also characteristic of yeast.
- Fragmentation. This type of reproduction is based on the body's ability to regenerate. It is characteristic of planaria, nemerthins, sponges, and some filamentous algae. With mechanical damage, the parent can be divided into several parts, each of which gives rise to a new organism.
- Sporulation, or spore formation. The most progressive type of asexual reproduction, since the formation of spores is the exchange of genetic information. As a result, the genotype of the offspring is somewhat different from that of the parent. Spore formation can be observed in fungi, algae, horsetail, ferns, throws, mosses.
What is the biological significance of asexual plant propagation?
The kingdom of the plant is conditionally divided into spore and seed. The first include mosses, horsetails, crowns, ferns, and the second - gymnosperms and angiosperms. Asexual reproduction of spore plants consists mainly in the formation of spores. In gymnosperms and angiosperms, spore formation remained as an intermediate stage in the emergence of gametes (microspores and megaspores). Reproduction with the help of the organs of the body - this is the biological significance of asexual reproduction in plants.
Vegetative propagation is characteristic only of highly developed representatives of the flora, and it is the only type of asexual reproduction. In spores such a method is extremely rare. Here, in fact, is another aspect of the biological significance of asexual reproduction in plants.
How is the reproduction of individuals vegetative?
- Modifications to the stem. These include bulbs, corms, rhizomes, stolons, tubers, mustaches. On such organs of the plant, buds are formed, from which new shoots grow. This method of reproduction can be found in tulips, daffodils, onions, blackberries, iris, strawberries, potatoes, etc.
- Root tubers (root tubers). These organs are subordinate roots in which nutrients are stored. Root plants propagate violet, Jerusalem artichoke, and dahlia.
- Cuttings. A cutle is any part of the stem that contains at least one node with the accessory buds. Sometimes just a leaf without a stem is enough for reproduction. Examples of plants: begonia, fuchsia, dracaena, etc.
The biological role of asexual plant propagation
The process of formation of gametes depends on many factors. Often, asexual reproduction can be more effective, because it can be done without gametes. For spore plants, this is the main component of the life cycle. For seed - this is vegetative propagation, in which you can easily increase the number of individuals.
What is the biological significance of asexual reproduction? It is not only speed, but also ease in the implementation of the process. If sexual reproduction requires optimal environmental conditions, the maturity of the plant itself, then asexual can be observed almost at any time during the life of an individual.
However, vegetative propagation has its drawbacks. For example, with this type of reproduction, genetic information is not exchanged. This means that the plant does not adapt in a number of generations to new environmental conditions, and this can lead to a loss of the population of the obtained clones.
The use of asexual reproduction of plants by humans
The reproduction process is actively used in business activities. Vegetative propagation of plants allows you to sow large tracts of land with potatoes, onions, beets, carrots, strawberries, strawberries, etc.
Also, vegetative propagation makes it possible to increase the number of valuable fodder, vegetable, ornamental crops, and to increase the plant's resistance to adverse environmental conditions through vaccination.