மியுடேஷன் Mutation Theory: Mutation Theory of Evolution by Hugo De vries | NEET Biology in Tamil science

மியுடேஷன் Mutation Theory: Mutation Theory of Evolution by Hugo De vries | NEET Biology in Tamil science #tamilbiology #neetbiology #neet #evolution #mutation #neetsyllabus #science Hugo de Vries (1848—1935), a Dutch botanist, one of the independent rediscoveries of Mendelism, put forward his views regarding the formation of new species in 1901. He also met some of the objections found in Darwin’s theory. According to him, new species are not formed by continuous variations but by sudden appearance of variations, which he named as mutations. Hugo de Vries stated that mutations are heritable and persist in successive generations. Salient Features of the Mutation Theory: On the basis of above observations, Hugo de Vries (1901) put forward a theory of evolution, called mutation theory. The theory states that evolution is a jerky process where new varieties and species are formed by mutations (discontinuous variations) that function as raw material of evolution. The salient features of mutation theory are: 1. Mutations or discontinuous variations are the raw material of evolution. 2. Mutations appear all of a sudden. They become operational immediately. 3. Unlike Darwin’s continuous variations or fluctuations, mutations do not revolve around the mean or normal character of the species. 4. The same type of mutations can appear in a number of individuals of a species. 5. All mutations are inheritable. 6. Mutations appear in all conceivable directions. 7. Useful mutations are selected by nature. Lethal mutations are eliminated. However, useless and less harmful ones can persist in the progeny. 8. Accumulation of variations produce new species. Sometimes a new species is pro­duced from a single mutation. 9. Evolution is a jerky and discontinuous process. Points in Favour of the Mutation Theory: (1) Mutations are actually the source of all variations and hence fountain head of evolution. (2) Mutation theory can explain both progressive and retrogressive evolution. (3) As the ratio of mutations is not the same in all indi­viduals and their parts, mutation theory can explain the occurrence of both changed and unchanged forms. (4) A number of mutations have appeared in the past. Mutations are also induced. They have given rise to new varieties. (a) Ancon Sheep (Fig. 7.49) is a short legged variety which appeared suddenly in Massachusetts in 1791. Points against the Mutation Theory (Criticism of the Mutation Theory): (1) Oenothera lamarckiana of Hugo de Vries was not a normal plant but a complex heterozygous form with chromosome aberrations. (2) Natural mutations are not common as Hugo de Vries thought them to occur. (3) Most of the mutations are negative or retro­gressive. (5) Mutation theory cannot satisfactorily explain the development of mimicry, mutual dependence of flowers and pollinating insects. (6) This theory does not explain the role of nature. Significance of Hugo de Vries’ Mutation Theory: Mutation is the natural and permanent change, causing changes in the DNA sequence in any living organisms. Variation or genetic variation is seen in an individual of any species, groups or population and is observed in genes as well as in alleles. ... Variations are seen in groups or populations of an individual Difference Between Mutation and Variation (with Comparison ...How do mutations cause variation? What are the 4 types of mutation? What is the difference between normal variation and genetic mutation? Is a variant a mutation? (4) Mutations are generally recessive while traits taking part in evolution are usually dominant. (b) Hornless Cattle developed as mutation from the homed cattle in 1889. (c) A single mu­tation can give rise to a new variety and even species of plants, e.g., Delicious Apple, Cicer gigas, Noval Orange, Red Sunflower, (d) Hairless cats and double­toed cats have developed through mutations. How are gene mutations involved in evolution? - Genetics ..› primer › mutations and disorders › evolution 5 days ago - Genetic variations can arise from gene mutations or from genetic ... the genetic variation is more likely to be passed to the next generation (a effects of mutation genetic variation gene mutation mutation definition biology causes of genetic variation mutation evolution examples gene flow types of genetic variation What is the genetic mutation theory? How do new species arise according to De Vries mutation theory of organic evolution? Who is the father of mutation? What is Saltation in evolution? mutation theory of evolution biology discussion mutation theory pdf mutation theory Slideshare mutation theory in Tamil mutation theory in tamil mutation theory example mutation theory of organic evolution synthetic theory of evolution Related Articles: Biological Evolution: Mechanism and Factors of Biological Evolution Hugo de Vries’ Mutation Theory : Salient Features and Advantages of Mutation Theory http://www.yourarticlelibrary.com/mutation Online tutorial in tamil, mechanism of evolution