Evolution in an accessible form for general development.
Evolution is a natural process of the development of life on Earth.
Evolution is a process of neontogenetic development, one-level qualitative transformation and / or degradation, a process of structural change of something from one state to another.
Biological evolution (from the Latin. Evolutio - "deployment") is a natural process of the development of wildlife, accompanied by a change in the genetic composition of populations, the formation of adaptations, speciation and extinction of species, the transformation of ecosystems and the biosphere as a whole.
There are several evolutionary theories explaining the mechanisms underlying evolutionary processes. At present, the synthetic theory of evolution (SHE), which is a synthesis of classical Darwinism and population genetics, is generally accepted. SHE allows us to explain the relationship between 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 alleles of genes in populations of organisms over a period of time longer than the lifespan of one generation.
Charles Darwin was the first to formulate the theory of evolution by natural selection. Evolution by natural selection is a process that follows from three facts about populations: 1) more offspring are born than they 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 individuals least adapted to the environment, which leads to an increase in the next generation of the proportion of such individuals whose traits contribute to survival and reproduction in this environment. Natural selection is the only known reason for adaptations, but not the only reason for evolution. Non-adaptive causes include genetic drift, gene flow, and mutations.
Despite the ambiguous perception in society, evolution as a natural process is a well-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 traditional areas of biology, but also on other academic disciplines, for example, anthropology, psychology. Ideas about evolution have become 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 over a period of time longer than the life of a single generation, and consists in changing the inherited features of an organism. The first stage of this process is the change in the frequencies of the alleles of the genes in the population. In an ideal population in which there are no mutations, natural selection, isolation (crossing selectivity), drift and gene flow, the frequency of alleles, according to Hardy-Weinberg, will be unchanged from generation to generation. Thus, the evolution in this population will not occur. However, in real populations there are factors that lead to changes in the frequencies of alleles of genes. These are mutations, gene flow, natural selection and gene drift. These factors are the factors of evolution. Mutations increase the variability in the population due to the emergence of new allelic variants of genes - mutational variability. In addition to mutational, there is also combinational 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 the emergence of new alleles, as well as changes in the frequencies of alleles. Another factor leading to a change in the frequencies of alleles is the flow of genes.