The evolutionary idea  proposed by Charles Darwin called ‘Darwinism’ or Natural selection theory, explaining the mechanism of evolution  is published in his book ‘ On the Origin of Species by means of Natural Selection’.

The important postulates of the theory are: Over production, Struggle for existence, Variations, Survival of the fittest, and Origin of species.

The recent supporters of Darwinism modified the theory according to the latest development in biology. This modified theory is called Neo- Darwinism or Modern synthetic theory of Natural selection.

A few Neo Darwinism Supporters are Romanes, Wallace, Fisher, Huxley, Ford, Haldane, Goldschmidt, Sewall Wright, Ernst Haeckel, August Weismann, Mendel, Dobazhansky , Kettlewell and Herbert Spencer.
Experimental Evidence for Natural Selection- Melanic and Non melanic moths

Darwinism vs Neo-Darwinism

1. It is the original concept postulated by Darwin and Wallace to explain the mode of organic evolution and resulting speciation.

2. It considers all inheritable favourable variations as driving force of speciation

3. It does not explain the reason for variation

4. In Darwin’s theory, the basic unit of evolution is an individual

5. It does not consider reproductive isolation as a major factor in new species formation

6. In Darwin’s theory, natural selection is the survival of the fittest and removal of the unfit ones during the course of time


1. It is the modification of original concept postulated by Darwin and Wallace with addition of data from Mendelian genetics, molecular biology, population genetics and biological species concept. 

2. It considers only inheritable genetic variation (mutations) for evolution

3. It explains the reason for variations. The major factors responsible for organic evolution include mutation, genetic recombination, natural selection and reproductive isolation.

4. In Neo-Darwinism, the basic unit of evolution is a population and the gene pool of the population undergoes variation

5. It consider reproductive isolation as a major essential factor in speciation

6. In Neo-Darwinism, Natural selection refers to the differential amplification of fittest genes and genotypes that is best suited to an environment 
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