Natural selection is the basic process of evolution, as a result of which the number of individuals is increasing in the population having the maximum adaptability (the most auspicious signs), while the number of individuals with adverse symptoms is reducing. In the light of the modern synthetic theory of evolution, natural selection is seen as the main reason for the development of adaptation, speciation, and the origin of supra-species taxa. Natural selection is the only known cause of adaptation, but not the only cause of evolution. The non-adaptive reasons include genetic drift, gene flow, and mutation.
The term natural selection was popularized by Charles Darwin, comparing the process with artificial selection, which modern form is selection. The idea of comparing artificial and natural selection is that in nature there is the selection of the most successful and best organisms, but in the role of evaluator of useful properties, in this case, not the person acts, but the habitat. In addition, the material for natural and artificial selection are small heritable changes that accumulate from generation to generation.
Charles Darwin thought that natural selection is was the main driving force of evolution. In the modern synthetic theory of evolution, it is also the principal regulator of the development and adaptation of populations, the mechanism of occurrence of species and supra-species taxa. Although in the late 19th - early 20th century, accumulation of information on genetics, in particular the discovery of discrete nature inheritance of phenotypic traits, led to some researchers denying the importance of natural selection. As an alternative they offered concepts based on an assessment of factors of genotype mutations as extremely important. Authors of such theories postulated not a gradual, but a very fast spasmodic character of evolution.
Discovery of known correlations among traits related species has led some researchers to the formulation of the next anti Darwin hypotheses about the evolution. In 1920-1940s in evolutionary biology, those who rejected the idea of Darwinian evolution by natural selection revived interest in this theory due to revision in the light of classical Darwinism a relatively young science of genetics. The synthetic theory of evolution developed after that was based on the quantitative analysis of allele frequencies in populations, changing under the influence of natural selection.
There are a lot of debates on the issue, where people with a radical approach, talks about the failure of classical synthetic theory of evolution to adequately describe all aspects of biological evolution.
Natural selection is the basic process of evolution, as a result of which the number of individuals is increasing in the population having the maximum adaptability (the most auspicious signs), while the number of individuals with adverse symptoms is reducing.