Synthetic theory of evolution

The synthetic theory of evolution was created on the basis of the unification in the 1920s of ecology, genetics and Darwinism. Today it is considered the most holistic and developed quite fully. The synthetic theory of evolution embodied population genetics and classical Darwinism.

The first who introduced a genetic approach was Chetverikov, Sergey Sergeevich. In 1926 he published an article where the evolution of life (in a number of moments) was considered from the point of view of genetics. In his work Chetverikov derived several provisions. As an example, he took natural populations of fruit flies. Thus, the scientist established:

1. Mutations under natural conditions occur constantly.
2. Recessive changes can persist indefinitely in the heterozygous state.
3. With the passage of time (as you age), mutations accumulate in the form, the signs of the species become unstable.
4. The main factors of intraspecific differentiation are hereditary variability and isolation.
5. Panmixia (free crossing) leads to polymorphism, and selection to a monomorphism of the species.

The theory presented by Chetverikov indicates that accumulation through random mutations contributes to an adaptively directed, regular flow in the course of development. The development of the exercise was continued by such Russian geneticists as Romashov, Timofeev-Resovsky, Vavilov, Dubinin and others. The work of these and other figures formed the positions on which the synthetic theory of evolution is based.

In the 30 years of the work of Wright, Haldemess, Fisher initiated the development of the teaching in the West.

One of the first works, where the synthetic theory of evolution was presented in its essence, was Dobzhansky's monograph on the origin of species and genetics. In this work, attention was focused on studying the mechanisms of formation of the genetic system of populations in accordance with the influence of various factors. Factors, in particular, include hereditary variability, fluctuations in the numbers of individuals in different populations, migration. Great influence was exerted by the causes of evolution, as well as the reproductive isolation of new forms formed within the species.

Outstanding is Schmalhausen's contribution to the development of the teaching. In accordance with the creative unification of embryology, evolutionary theory, paleontology, morphology, and also genetics, the scientist conducted in-depth studies of the correlation between phylogenesis and ontogeny, studied the main trends in evolution, and also developed several fundamental provisions of modern teaching.

Among fundamental studies, Huxley's work Evolution, Modern Synthesis occupies an important position. Of great importance were also the studies of the forms and rates of development undertaken by Simpson.

Synthetic theory is based on eleven major postulates. Vorontsov formulated them in a concise form.

1. Mutations, being small discrete changes in heredity, are considered evolutionary material, which is of an accidental nature.
2. The main, to some extent even the only driving force of development is natural selection, which is based on the selection of small and random mutations.
3. The smallest evolving unit is the population.
4. Development has a gradual (gradual) and lasting character.
5. The species includes many subordinate and at the same time distinguishable (morphologically, genetically, physiologically), but not isolated reproductive units.
6. Evolution involves a divergence of symptoms.
7. The flow of genes (exchange of alleles) is allowed only within the species. In this regard, he (the species) is considered a holistic and genetically closed system.
8. Properties of the species do not refer to forms that reproduce asexually and parthenogenetically.
9. Macroevolution takes place through microevolution.
10. The real taxon has a monophylitic origin (refers to one ancestral species).
11. Evolution is a process unpredictable, has a character that is not directed toward the ultimate goal.