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Modern Synthetic Theory of Evolution

Modern Synthetic Theory of Evolution

The Modern Synthetic Theory of Evolution describes the evolution of life in terms of genetic changes occurring in the population that leads to the formation of new species. It also describes the genetic population or Mendelian population, gene pool and the gene frequency. The concepts coming under this synthetic theory of evolution include the genetic variations, reproductive and geographical isolation and the natural selection.

The Modern Synthetic populations of Evolution describes the merging of the Darwinian evolution with the Mendelian genetics, resulting in a unified theory of the evolution. This theory is also referred to as the Neo-Darwinian theory. Synthetic theory of Evolution was introduced to us by few legendary evolutionary biologists naming T. Dobzhansky, J.B.S. Haldane, R.A. Fisher, Sewall Wright, G.L. Stebbins, Ernst Mayr in the years 1930 and 1940.

The Modern Synthetic Theory of Evolution showed a number of changes as to how the evolution and the process of evolution are conceived. The theory gave a new definition about the evolution as “the changes occurring in the allele frequencies within the populations, ” which emphasizes on the genetics of evolution.

The modern synthetic theory includes scientific evidence from genetics. It explains the concepts which occur when the allele frequency of the population changes. According to this theory, when the changes are great enough, there is a formation of new species. A species is a group of individuals who are capable of interbreeding and producing a fertile offspring.

Factors of Modern Synthetic Theory of Evolution

There are some factors describing the modern theory of synthetic evolution which are as explained below-

In addition to these reactions, the other factors affecting the working of the process are the migration of the individuals from one form of the population to other, hybridization between the races of species increases the genetic variability of the popu­lation.

Recombination or Variation

Recombination of the new genotypes from the existing genes. The gene combinations having same indi­viduals with two kinds of alleles, mixing of the chromosomes during sexual reproduc­tion of two parents produce new individuals, an exchange of the chromosomal pairs of alleles during the meiosis which is called crossing overproduce the new form of gene combinations. Chromosomal mutations like deletion, inversion, duplication, translocation, polyploidy result in the recombination.


The changes that occur in the gene due to phenotypic effect differential as the mutation. This produces a variety of changes that may be harmful. Many of the mutant forms of genes are recessive to the normal genes in a homozygous condition. These mutations cause variations in offsprings.


The transmission occurring in the variations from the parents to their offsprings is a primary mechanism in the evolution. The organisms which possess hereditary properties are favoured in the struggle for the existence. By this, the offsprings benefit from the characteristics of parents.

Natural selection

Natural selection produces a change in the frequency of the genes from one generation to the other favouring the differential form of the reproduction. The natural selection process creates an adaptive relation between the environment and the population through various combinations of genes.


It is one of the significant factors responsible for the synthetic theory of evolution. The isolation helps in preventing the interbreeding of related organisms which is a reproductive form of isolation.

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