Natural selection is one of the main processes of evolution of living organisms. What is the biological significance of natural selection? What mechanisms does nature possess for its implementation?
The emergence of theory
The idea that today's appearance of organisms is the result of long evolutionary processes began to ripen in the 19th century. At that time several scientists dealt with this issue. Back in 1855, Alfred Russell Wallace published his article, which he devoted to thinking about evolution through natural selection.
The idea of ​​Wallace was immediately picked up by Thomas Malthus, writing the work "Experience on the Law of Settlement." He suggested that the purpose of each population is reproduction, and when the number of individuals becomes too large, some of them die. Here, by the way, Wallace’s thought came about that it was not random organisms that died, but the weakest.
The theory of natural selection was also reflected in Charles Darwin's Origin of Species (1859). The scientist came to his conclusions after a round-the-world expedition aboard the Beagle ship of 1831-1836. And although his work was published later than Wallace's article, it was Darwin who became the main conductor of this hypothesis, challenging the supporters of the divine origin of all living things.
What is the biological significance of natural selection?
Evolutionary theory has long been rejected, even now many consider it a fabrication. However, the existence of natural selection is difficult to refute. Its main principle can be formulated as follows - "the strongest survives."
The natural selection of C. Darwin is that nature constantly weeds out weak individuals. We observe a similar situation with artificial selection, when the gardener chooses the most suitable and viable sprouts for planting in the ground. Wildlife does the same.
So what is the biological significance of natural selection? First of all, in a qualitative improvement in the population. In conditions of changing habitat, if the population number increases sharply, living organisms may have difficulty in obtaining food or other resources. They are forced to get used to other conditions. Anyone who does it better can survive, which means that he will pass off more powerful genes to offspring.
Natural selection is one of the engines of evolution. In the course of adaptation to changing conditions, living organisms develop new devices and mechanisms. They can change behavior or their appearance, and over time they are very different from their ancestors.
Examples of natural selection in animals
Natural selection is a kind of rivalry within one species. One of its options is sexual selection, which exists in almost everyone. Animals do not realize what the biological significance of natural selection is and what it is. However, they constantly follow his laws.
Female birds choose a partner with brighter plumage. Other animals are guided by the sizes of tails, horns. Often males have to prove their superiority by mating dance or a duel with an opponent.
An example of natural selection is the adaptation of insects to pesticides. The use of the same substances to kill pests often leads to the development of their immunity and resistance to drugs.
Many desert inhabitants were forced to develop special adaptations in order to survive in harsh conditions. The lack of regular precipitation led to the formation of humps in camels. Lizards with paws help the lizards easier to move on sand, long jumps help the jerboa, and snakes even learned to crawl.
Plant Examples
According to the mechanisms of adaptability, plants are not inferior to animals. Cacti, for example, have spines. They occupy a smaller area than the leaves, and prevent the rapid evaporation of moisture.
Other examples of natural selection from plants can be found in any forest where competition is active. In shady areas, usually lower and weaker trees will grow than those that grow in sunny areas. The latter will receive more light and heat, which means they have more chances for full development.
Of course, this example is valid only for photophilous plants. Species that formed in humid and shady areas have long adapted to these conditions. As a result of natural selection, they developed wide leaves. They rarely bloom because they do not receive enough sunlight.