The term ‘mutation’ was introduced by Hugo de Vries. The term was used by de Vries for large spontaneous inheritable changes, which occur suddenly in naturally reproducing populations.
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Mutation Theory of Hugo de Vries (1901):
Hugo de Vries Mutation theory was based upon his observations on evening primrose i.e. Oenothera Lamarckiana growing wildly in a field near Amsterdam. Hugo de Vries studied 54343 plants of Oenothera in a period of eight years.
Mutation theory established that “new species originate as a result of these large, discontinuous variations which appear suddenly and full-fledged and from the new species at once”.
The main features of Mutation Theory are:
Mutations arise from time to time amongst the individuals of a naturally breeding population or species. The individuals with mutations are known as mutants. These mutants are markedly distinct from their parents.
Mutations are inheritable and establish new forms or races or species.
Mutations are large and sudden and are totally different from fluctuating variations of Darwin, which are small and directional.
Mutations may occur in any direction.
Mutations are subjected to natural selection.
Mutants found unsuitable are likely to be destroyed by natural selection.
Since mutations appear full-fledged, there is no question of development of organs from the incipient stages.
Darwinists contended that evolution resulted from gradual fluctuating inheritable differences over a long series of generations, whereas mutationists believed in the sudden appearance of species differences.
B.A.Davis discredited mutation theory by claiming that Oenothera Lamarckiana is of hybrid nature, which could be produced by crossing two wild American species.
We may conclude by saying that Hugo de Vries mutation theory based on changes, that were not genetic mutations, was fundamentally correct in stressing the significance of mutations in the evolutionary process. However, mutations alone cannot account for evolution, but these furnish the raw material on which other forces can act to bring about evolutionary change.