Natural selection and fight for existence

Natural selection increases chances of survival and continuation of all sort, it costs at one step with mutations, migrations and transformations in genes. The main mechanism of evolution operates smoothly, but provided that nobody interferes with its work.

What is natural selection?

The English scientist Charles Darwin gave to this term value. He established that natural selection is a process which defines survival and reproduction only of the individuals adapted for environmental conditions. According to Darwin's theory an important role in evolution is played by random hereditary changes.

• recombinations of genotypes;
• mutations and their combinations.

Natural selection at people

At the time of undeveloped medicine and other sciences only the person having strong immunity and a resistant healthy organism survived. Premature newborn children were not able to be nursed, in treatment did not apply antibiotics, did not do operations, and it was necessary to cope with the illnesses independently. Natural selection took away the strongest representatives of mankind for further reproduction from people.

In the civilized world it is not accepted to get numerous posterity and in most of families no more than two children who thanks to modern living conditions and medicine, can quite live to a ripe old age. Earlier in families there were about 12 children and more, and survived under favorable conditions no more than four. Natural selection at the person led to the fact that in the majority the tempered, exclusively healthy and strong people survived. Thanks to their gene pool the mankind still lives on the earth.

Reasons of natural selection

All life on the earth developed gradually, from the simplest organisms - to the most difficult. The representatives, any given life forms who did not manage to adapt to the environment did not survive and did not reproduce posterity, genes them were not transferred to the subsequent generations. The role of natural selection in evolution led to emergence of ability at the cellular level to adapt to the environment and to react quickly to its changes. The reasons of natural selection are influenced by a number of the simplest factors:

1. Natural selection works when into world it is brought descendants more, than can survive.
2. At genes of an organism there is a hereditary variability.
3. Genetic distinctions dictate survival and ability to reproduction of posterity in different conditions.

Signs of natural selection

Evolution of any living organism is a creativity of the nature and it is not its whim, but need. Working in various conditions environments, it is not difficult to guess what signs are kept by natural selection, all of them are directed to evolving of a look, increase in its resistance to external influences:

1. The selecting factor plays an important role. If in artificial selection of people chooses what signs of a look to keep and what are not present (it is admissible at removal of new breed of dog), then at natural selection wins against the strongest in fight for the existence.
2. Material for selection are hereditary changes which signs can help with adaptation to new living conditions or for specific goals.
3. The result is another step of natural selection following the results of which new views with the signs bringing benefit in any given environmental conditions were created.
4. Action speed – Mother Nature does not hurry anywhere, considers each step and therefore for natural selection the low speed of changes, is characteristic of artificial - fast.

What is result of natural selection?

All organisms have the degree of adaptability and it is impossible to tell with confidence as any given look will behave in unfamiliar environmental conditions. Fight for survival and hereditary variability is an essence of natural selection. There are many examples of plants and animals who were delivered from other continents and who took root better in new living conditions. Result of action of natural selection are the whole set of the acquired changes.

• adaptation – adaptation to new conditions;
• a variety of forms of organisms – arise from the general ancestor;
• evolutionary progress – complication of types.

What does natural selection differ from artificial in?

It is possible to tell with confidence that practically everything that is eaten by the person sooner or later was exposed to artificial selection. The basic difference only that making "the" selection the person pursues own benefit. Thanks to selection he received perfect products, removed new breeds of animals. Natural, natural selection is focused it is not good for mankind, it pursues only the interests of this concrete organism.

Natural and artificial selection equally influence life of all people. For life of the premature child fight, as well as for life healthy, but at the same time, natural selection kills the drunkards who froze on streets, fatal diseases claim the lives of ordinary people, mentally unstable finish life with suicide, natural disasters fall upon the earth.

Types of natural selection

Why in different environmental conditions only certain representatives of types are capable to survive? Forms of natural selection are not hand-written rules of the nature:

1. Driving selection happens when environmental conditions change and types should adapt, it keeps genetic heritage in certain directions.
2. The stabilizing selection – is directed to individuals with deviations from average norm in favor of average individuals of the same look.
3. Dizruptivny selection, it when individuals with extreme indicators, but not with average survive. Two new views can be formed as a result of such selection at once. Meets at plants more often.
4. Sexual selection – is based on reproduction when a key role is played not by(with) ability to survive, and appeal. Females, without thinking of the reasons of the behavior, choose beautiful, bright males.

Why the person is capable to weaken impact of natural selection?

Progress in medicine stepped far ahead. People who had to die - survive, develop, bring the children. Transferring them the genetics, they generate a weak sort. Natural selection and fight for existence face hourly. The nature thinks out more and more sophisticated ways of control over people, and the person, tries not to lag behind it, thereby interfering with natural selection. Human humanity leads to a weak type of people.

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