Following are the points of Darwin's theory of natural selection:
(i) Over-production: Every organism has enormous potential to reproduce.
(ii) Struggle for existence: Population size of an organism is limited due to struggle between the members of same species as well as the members of different species. It is due to struggle for food, space and mate.
(iii) Variation: Due to struggle, the fit organisms possess some variations which are favourable, and they can leave the progeny to continue the favourable variations.
(iv) Survival of the fittest: The fittest organism survive to continue the favourable variations.
(v) Formation of a new species: These variations when accumulated for a long time, leads to the origin of a new species.