Question

Darwin in his “Natural Selection Theory” neglected the role of which one of the following?

• A. Overproduction
• B. Survival of the fittest
• C. Struggle for existence
• D. Discontinuous variations

Answer 1

The correct option is D Discontinuous variations

Darwin proposed the theory of natural selection. This theory was based on certain key points as follows:

• Overproduction: All organisms reproduce more offspring than that can actually survive. For example - pair of mice produces dozens of young ones.
• Struggle for existence: A struggle or competition occurs among the organisms to obtain the available resources. This struggle may be interspecific (between different species), intraspecific (within the same species) or with the environment.
• Variations: Individuals may develop continuous variations (smaller changes favoured by nature) over generation, this will help them to better adjust towards the surroundings or environment.
• Natural selection or survival of the fittest: The individuals with favourable variations have a better chance of survival and those organisms/individuals are selected by nature.
• Inheritance of useful variations: Useful variations present in the present generation are passed to the next generation.
• Origin of new species: The favourable variations accumulate over the generations and ultimately form new species from the original ones.

Darwin, in his “Natural Selection Theory”, did not believe in the role of discontinuous variations. Discontinuous variations are large, sudden changes in the organisms (mutations). Darwin believed in the small continuous variations (small changes occurring in the course of time and which are favoured by nature). Those variations which are helpful to an individual towards adapting to its surroundings would be passed onto the next generation. But Darwin did not understand the cause of variation and assumed it was one of the innate properties of living things. Whereas Hugo de Vries through his mutation theory explained the cause of variation. He proposed that the variations are due to mutation (sudden and large changes) and thus, they may be discontinuous. So, discontinuous variation is a part of mutation theory, not natural selection of Darwin.