Evolution — BIOLOGY STD 12 Science — Question

Hugo de Vries (1901) experiment on Evening Primrose (7'0 clock plant) revealed that some plants suddenly become completely different from their own species. Not only this, various traits are inherited and passed from one generation to the next and create new species. De Vries termed sudden hereditary changes inherited form one to next generation as mutation and propounded the theory of mutation. It has also been known, from modern research that mutation in living organisms is caused by changes in the arrangement, structure and sequence of chromosomes and genes located in germ cells of organisms.
Following are the facts of DeVries's mutation theory :
1. Naturally reproducing species or species develop mutations from time to time. Mutant organisms are different from parent life.
2. Mutations are hereditary and lead to the development of new species.
3. Mutation appear all of a sudden. They become operational immediately.
4. Mutations are the raw material of evolution.
5. They can occur in any direction, hence they can be both beneficial and harmful.
6. Natural selection has an effect on mutation. Useful mutations are selected by where as Lethal mutations are eliminated however useless and less harmful once can persist in the progeny.
7. Darwin named these sudden changes as sports.
8. Excessive specialization of organs is explained by these sports or the initial stage of development of organs can be explained by the theory of mutation because mutations are complete from the beginning.
Importance of Mutation : There is not the slightest doubt that mutations occur in nature and their role in development. Natural selection and isolation of were also essential for evolution.