Selection - what is it? Selection of plants and animals

The founder of the concept of "selection" is Charles Darwin, who was able to describe the role of hereditary variability and artificial selection in the creation and breeding of new breeds and varieties.

What is selection?

The definition is formulated as follows: "Breeding is a science that studies methods of creating and improving cultivar cultivars , breeds of domestic animals and strains of microorganisms."

A variety or breed is a population created by a man in an artificial environment, which has invaluable benefits for a person: he possesses useful hereditary traits, high productivity, necessary physiological and morphological parameters.

Breeding (what it means - thoroughly studying biology) is characterized by the appearance of breeds of domestic animals, as well as new varieties of cultivated plants that have arisen as a result of artificial selection, which can only be carried out by a person.

Cultural forms are characterized by the fact that they have very strong development of certain signs with which the body is difficult to exist in a natural environment, but for a person they are useful. A vivid example is the chicken's ability to give three hundred eggs per year. In nature, such a feature of the bird is meaningless, since the chicken can not sit three hundred eggs.

Historical facts

At the beginning of its existence was a method of artificial selection of selection. What is laborious long-term work aimed at obtaining a certain useful attribute - only the breeders themselves know. Until the seventeenth century, selection was unconscious. For example, a person chose the largest seeds to get a good harvest, without even thinking that the plant is already changing in the direction necessary for the person.

And it was only about a hundred years ago that a man began, not yet studying the principles and laws of genetics, to purposefully and consciously interbreed such plants that maximally satisfied human desires and needs.

But only by the method of artificial selection man could not create new species of living organisms. Using this method, we can distinguish only those genotypes that already exist in the population. That is why currently used hybridization, which allows you to get completely new varieties of plants and breeds of animals.

What is plant breeding?

The most important methods of plant breeding are hybridization and selection. For cross-pollinated plants, a mass selection of the desired properties is used. Otherwise, you can not get the material necessary for further work. Thanks to this method, new varieties of cross-pollinated plants (for example, rye) can be obtained. Such varieties will not be genetically homogeneous. But to obtain a clean line scientists use individual selection, during which, as a result of self-pollination, you can get quality specimens with the necessary characteristics and attributes.

For plant breeding, experimental polyploidy is very often used, since each polyploid is characterized by high yield, large size and relatively rapid growth.

There is also a method of artificial mutagenesis, which was considered by Vavilov. An organism that has mutated and acquired new properties is called a mutant, and the process of transfiguration is a mutation.

Features of animal breeding

What is the selection of animals - it is not difficult to answer. It is very similar to plant breeding, but it still has some peculiarities. It should be borne in mind that for animals only sexual reproduction is characteristic. Due to the very rare generation change (in many animals a few years later), the number of individuals in the offspring is extremely small. That is why, when carrying out selection works, scientists should conduct an analysis of all external characteristics characteristic of a particular breed.

Domestication

What is selection in biology? The definition is given in the school curriculum. The most important achievement of mankind was the domestication of wild animals more than ten thousand years ago. Thus, people have a constant source of food.

For domestic animals is characterized by the presence of special signs, which are very often harmful to natural existence, but for a person they have an invaluable positive value. The factor of domestication is the artificial selection of individuals that meet human requirements. People chose animals that had a good appearance, a calmer character and other qualities important for a person.

After the unconscious methodical selection has appeared. Its purpose is to form the animals necessary and useful qualities.

The method of domestication of new animals is practiced by man even now. It is necessary for him, for example, to get high-quality furs. Thus, a new branch of the economy - fur farming.

Crossing and selection

Selection (what does it mean for humanity - you can learn by reading this article) also considers such a method as crossing animals. This is done to improve the appearance, quality of meat or increase the fat content of milk. Individuals that are bred are evaluated not only by their appearance, but also by the quality of their offspring. That's why it's very important to study their pedigree.

At the moment, there are two types of crossing: outbreeding and inbreeding. The first type is characterized by the crossing of individuals not only of one but also of different breeds. Further strict selection is able to maintain useful qualities and increase their number in offspring.

During inbreeding, parents and offspring, or brothers and sisters, are used. Due to this crossing, homozygosity is increased and valuable traits in offspring are fixed.

Remote hybridization has a relatively low effect, because interspecific animal hybrids are most often infertile.

What is the selection of standardization objects? This concept characterizes the activity, which consists in the selection of certain objects that are considered suitable for their further production, and application in all spheres of human life.

Selection of microorganisms

Microorganisms play a very important role in the biosphere, and directly in human life. Humanity uses several hundred microorganisms, and their number is growing every year.

The selection of microorganisms is characterized by a number of features. Breeders in stock have an infinite amount of material. Since the gene of any microorganism is haploid, scientists can identify a mutation in the first generation. Bacteria have a relatively small number of genes, so the work is much easier and faster.

Bacteria can independently produce substances useful to humans, and this is their property that uses microorganisms for breeding. What is the genetic engineering method in this industry? This is a set of influences that provokes bacteria to produce such compounds that are not naturally produced.

Sometimes breeders use transduction - transfer necessary DNA from one bacterium to another and thus increase the importance of microorganisms for the environment.

An important method of breeding with microorganisms is the hybridization of different strains. This method allows you to combine materials that can not meet in nature.

How the selection works are conducted

What is selection in biology? The definition allows you to learn about new improved varieties, strains and populations of living organisms. To date, all the selection work is carried out taking into account the needs of the agricultural market and production. For example, scientists have developed a unique technology for the utilization of petroleum products, with the ability to turn them into a protein-vitamin useful product. Such an achievement was due to the selection of strains of bacteria.

What is selection in biology? A very important direction of applied science, which allows people to get quality food and new types of modern production.