Natural selection is one of the main processes of evolution of living organisms. What is the biological significance of natural selection? What mechanisms for its implementation owns nature?
The idea that today's appearance of organismsis the result of long evolutionary processes, began to mature in the XIX century. At that time several scientists were engaged in this issue. Back in 1855, Alfred Russell Wallace published his article, which he devoted to reflections on evolution through natural selection.
The idea of Wallace immediately picked up by Thomas Malthus,writing the work "Experience of the law of settlement." He suggested that the goal of each population is reproduction, and when the number of individuals becomes too large, some of them die. By the way, Wallace had the idea that it is not the random organisms that are killed, but the weakest.
The theory of natural selection is reflected inthe work of Charles Darwin "The Origin of Species" (1859). The scientist arrived at his conclusions after an around-the-world expedition aboard the Beagle ship of 1831–1836. And although his work was published after Wallace's article, it was Darwin who became the main conductor of this hypothesis, challenging supporters of the divine origin of all life.
Evolutionary theory has long been rejected,even now, many consider it an invention. However, the fact of the existence of natural selection is difficult to refute. Its basic principle can be formulated as follows: “the strongest survives.”
Natural selection Ch.Darwin is that nature constantly sifting out weak individuals. We see a similar situation with artificial selection, when the gardener selects the most suitable and viable sprouts for planting in the ground. Wildlife does the same.
So, what is the biological significance of naturalselection? First of all, in the qualitative improvement of the population. In a changing habitat environment, if the population number increases dramatically, living organisms may experience difficulty in obtaining food or other resources. They are forced to get used to other conditions. Anyone who does it better will be able to survive, and therefore, will give offspring more powerful genes.
Natural selection is one of the enginesevolution. In the course of adaptation to changing conditions, living organisms develop new adaptations and mechanisms. They can change the behavior or their appearance, and over time are very different from their ancestors.
Natural selection is a kind ofrivalry within the same species. One of its options is sexual selection, which exists in almost all. Animals do not realize what the biological significance of natural selection is and what it is. However, they constantly follow his laws.
Females of birds choose a partner with a brighterfeathering Other animals are guided by the size of the tails, horns. Often males have to prove their superiority with a mating dance or a duel with a rival.
An example of natural selection can serveadaptation of insects to pesticides. The use of the same substances for the destruction of pests often leads to the development of their immunity and drug resistance.
Many desert dwellers were forced todevelop special adaptations to survive in harsh conditions. The lack of regular rainfall led to the formation of humps on camels. It is easier to move along the sand to lizards help scales on their paws, jerboa - long jumps, and snakes have learned to crawl.
Plants on the mechanisms of adaptability in no way inferior to animals. Cacti, for example, have spikes. They occupy a smaller area than the leaves, and prevent the rapid evaporation of moisture.
Другие примеры естественного отбора у растений can be found in any forest where competition is active. In shady areas, low and weaker trees will usually grow than those that grow on sunny terrain. The latter will receive more light and heat, and therefore have a better chance for full development.
Of course, this example is valid only forphotophilous plants. Species that were formed in wet and shady areas have long adapted to these conditions. As a result of natural selection, they developed wide leaves. They rarely bloom, as they do not get enough sunlight.
