Evolution in an accessible form for general development
Evolution is the natural process of the development of life on Earth.
Evolution is a process of non-developmental development, one-level qualitative transformation and / or degradation, a process of structural change from something to another.
Biological evolution (from Latin evolutio - "unfolding") is a natural process of development of living nature, accompanied by a change in the genetic composition of populations, the formation of adaptations, species formation and extinction of species, the transformation of ecosystems and the biosphere as a whole.
There are several evolutionary theories that explain the mechanisms underlying evolutionary processes. At the moment, the synthetic theory of evolution (STE), which is a synthesis of classical Darwinism and population genetics, is generally accepted. STE makes it possible to explain the relationship of the material of evolution (genetic mutations) and the mechanism of evolution (natural selection). Within the framework of STE, evolution is defined as the process of changing the frequencies of gene alleles in populations of organisms for a time longer than one generation.
Charles Darwin was the first to formulate the theory of evolution through natural selection. Evolution through natural selection is a process that follows from three facts about populations: 1) more offspring are born than can survive; 2) different organisms have different traits, which leads to differences in survival and the probability of leaving offspring; 3) these traits are inherited. These conditions lead to the emergence of intraspecific competition and selective elimination of the individuals least adapted to the environment, which leads to an increase in the next generation of the proportion of such individuals whose features contribute to survival and reproduction in this environment. Natural selection is the only known cause of adaptation, but not the only reason for evolution. Non-adaptive causes include genetic drift, gene flow and mutation.
Despite ambiguous perception in society, evolution as a natural process is a firmly established scientific fact, has a huge amount of evidence and does not cause doubts in the scientific community. At the same time, certain aspects of theories explaining the mechanisms of evolution are the subject of scientific discussions. Discoveries in evolutionary biology have had a tremendous impact not only on the traditional fields of biology, but also on other academic disciplines, such as anthropology, psychology. Representations about evolution became the basis of modern concepts of agriculture, environmental protection, are widely used in medicine, biotechnology and many other socially significant areas of human activity.
Evolution occurs during a period of time that exceeds the life span of one generation, and consists in changing the inherited features of the organism. The first step in this process is the change in the frequencies of gene alleles in the population. In an ideal population in which there are no mutations, natural selection, isolation (selectivity of crossing), drift and the flow of genes, the frequency of alleles, according to the Hardy-Weinberg law, will be unchanged from generation to generation. Thus, evolution in this population will not occur. However, in real populations there are factors that lead to changes in the frequencies of gene alleles. These are mutations, the flow of genes, natural selection and drift of genes. These factors are factors of evolution. Mutations increase the variability in the population due to the appearance of new allelic variants of genes - mutational variability. In addition to the mutational one, there is also a combinative variability due to recombination. Usually it does not lead to changes in the frequencies of alleles, but to their new combinations. However, gene conversion can lead to both the appearance of new alleles and changes in allele frequencies. Another factor leading to a change in allele frequencies is the flow of genes.