The basic postulates of Darwinism are:
(i) Enormous Power of Fertility: Every living organism has power to reproduce rapidly. Hence there is a danger of population overrunning the food and other facilities. As a result there are chances of elimination of a number of individuals because the available resources are less and that has resulted in competition among organisms where every individual tries to be better than the other. Darwin suggested that population of each species remains more or less constant because offspring perish in good number before themselves becoming capable of reproducing.
(ii) Struggle for Existence : Over population resulted in struggle which Darwin called the struggle for existence.
Which are of three types:
1. Intra-specific struggle: The struggle within the species.
2. Inter-specific struggle: The struggle between different groups of animals. e.g. carnivorous animals eat the lower animals.
3. Environment struggle : Struggle with the adverse environmental conditions, such as extreme temperature, lack of sunlight, nutrients etc.
(iii) Variations and Heredity: During competition every indivdes become better and shows variation. But at the vartions are not evolutionary point of view. Some may be useful and seal The metal variations are inherited in progeny of those orgams in which they therefore, the progeny have better chances of survival
(iv) Survival of the Fittest or Natural Selection: Daring struggle for extence only those individuals which are better adapted to the environment and favourable variations are selected. The less fit and unfit individuals arched by nature. Darwin stated that the variations are sorted out naturally. Therefore, t organisms which sort out such variations are said to be fittest
(v) Origin of Species: According to Darwin, new variations appear in every generation and get inherited to the new generation. As a result, the offsprings am distinct from their ancestors. This results in the formation of new species Gradual modification of the existing species leading to the formation of new species is known as speciation.
