The synthetic theory of evolution , also known as neodarwinismo, refers to the scientific contributions made over the years to the theory of evolution of the species, proposed by Charles Darwin in 1859 in his book"The origin of the species".
The synthetic theory of evolution suggests that the concepts of genetics (originally introduced by Gregor Mendel ) are a fundamental part of evolution, and also integrate paleontological and taxonomic knowledge, through which it is possible to deepen the study of the evolutionary processes of species.
There were many scientists who developed the studies on which the synthetic theory of evolution is based.
The most outstanding were Ronald Fisher, John Haldane, Sewall Wright, Julian Huxley, Ernst Mayr, Bernard Rensch, George Stebbins and George Simpson.
However, it is considered that the geneticist Theodosius Dobzhansky was one of the main integrators of the different hypotheses that arose around the Darwinian theory.
In 1937, Dobzhansky published the book"Genetics and Origin of Species", which contained the results of his research related to mutations and the generation of new species from these variations.
The synthetic theory of evolution gives importance to the laws of inheritance, through which it was possible to explain how genetic information is transmitted from one individual to another, and what are the reasons why this process of transmission occurs.
In addition to the hereditary domain, the synthetic theory of evolution also considers in a special way the discoveries of fossils and prehistoric elements, which allow to identify the variations existing in the different individuals of the same species.
The findings in paleontology can give indications as to the way in which these variations occurred and the reasons that propitiated them. And they also concretely expose the durability over time of these variations.
Among the main precepts of the synthetic theory of evolution are the conception of populations as units of evolution, the recognition of genes as the elements that transmit hereditary information, and the ratification of natural selection as a fundamental element in the evolution of the species.
Main precepts and characteristics that define the synthetic theory of evolution
Theories contrary to Darwinism are discarded
The theory of evolution of species, proposed by Charles Darwin, is the basis on which the synthetic theory of evolution is based.
For this reason, the representatives of this theory give priority to Darwin's theory, and reject all contrary hypotheses.
The phenotype and genotype concepts differ
Thanks to the recognition of genetics as a fundamental part of the evolutionary process, a distinction is made between the phenotype (those physical characteristics of the individuals) and the genotype (relative to the genetic information that beings have).
You may be interested What are Genotype Variations? Types and Examples .
Evolution is generated by five processes
The synthetic theory of evolution contemplates five forms through which evolution can take place:
1- Mutation
It refers to those alterations that the offspring can inherit. These variations may be beneficial to the species, may be harmful, or may even be neutral (ie, they have no role in species adaptation, so they are indifferent).
According to this theory, mutation occurs randomly and is the only way through which new genes are generated in organisms.
Genetic recombination
It does not have to do with the creation of new genes, but with the generation of new combinations of existing genes.
Through these new combinations, it is possible to generate variations in species.
3- Gene drift
This term refers to the random characteristic that may have the generation of genotypes. This transformation takes place over several years; that is, that the variations are visible after several generations.
The synthetic theory of evolution stipulates that chance only intervenes in gene drift, it does not participate in any other way.
4- Insulation
This concept refers to the inability to reproduce species that do not match physically. This non-coincidence of individuals can be due to the effect of physical barriers, such as great distances separating individuals from species.
Isolation can also occur when individuals are in the same geographic space but do not coincide, for example, their sexual maturation moments, when they have different mating routines or general functioning, when there is incompatibility of sexual cells, among other reasons.
5- Natural Selection
According to this concept, the beings that survive in a certain context will be those that have the characteristics that best suit their environment.
When reproduction is due to this beneficial characteristic, the genes corresponding to that characteristic will be passed on to the next generation.
This means that, through natural selection, it is possible for sustained variations and even new species to be generated.
Evolution is seen as a population process
According to the synthetic theory of evolution, it is the populations that evolve.
In order for the survival of a species to be generated in a given context, there must be a considerable number of individuals of that species that survive.
For this reason, individuals are not the protagonists of evolutionary processes, but the large groups of individuals.
This is the reason why the object of study on which this theory is based is the genetics of populations.
Discuss whether evolutionary changes are gradual or abrupt
Within the framework of the synthetic theory of evolution, a trend emerged which stipulated that physical evolutionary changes were not always gradual, but that great changes could be made abruptly, depending on factors giving rise to variations in individuals of the species .
This was the theory of punctuated equilibria, proposed by Niles Eldredge and Stephen Jay Gould in 1972.
They were based on paleontological studies to determine that it is possible to generate phenotypic variations in species without intermediate links between individuals with different characteristics.
References
- Pedroche, F."The modern synthesis in Biology. Eclecticism or the complementarity of a great paradigm"in Metropolitan Autonomous University. Retrieved on 3 September 2017 from Universidad Autónoma Metropolitana: uam.mx.
- Collado, S."Theory of Evolution"in Philosophica. Retrieved on 3 September 2017 from Philosophica: philosophica.info.
- "Neo-Darwinism"at Autonomous University of Guadalajara. Recovered on 3 September 2017 from Autonomous University of Guadajara: campusdigital.uag.mx.
- "Synthetic theory"at the National Autonomous University of Mexico. Retrieved on 3 September 2017 of Universidad Nacional Autónoma de México: portalacademico.cch.unam.mx.
- Ayala, F."Evolution"in Encyclopedia Britannica. Retrieved on 3 September 2017 from Encyclopedia Britannica: britannica.com.
- "Modern Synthesis"in Encyclopedia. Retrieved on 3 September 2017 from Encyclopedia: encyclopedia.com.
- "Neo-Darwinism / Synthetic theory of natural selection / Modern theory of evolution"in Sea Athanasius College. Retrieved at 3 September 2017 of Mar Athanasius College: macollege.in.
- "The Beginning of the"Modern Synthesis": Theodosius Dobzhansky"in Spanish Society of Evolutionary Biology. Retrieved on 3 September 2017 of Spanish Society of Evolutionary Biology: sesbe.org.
- Salas, N. and Iturbe, U."Evolution: the unfinished synthesis"in Academia. Retrieved on 3 September 2017 from Academia: academia.edu.
- "Punctuated equilibrium"at the National Autonomous University of Mexico. Retrieved on 3 September 2017 of Universidad Nacional Autónoma de México: portalacademico.cch.unam.mx.