Due to the process like tendency of living organisms of rapid reproduction, but limited food resources, space and ecological niches.

There occurs interspecific and intraspecific struggle for the basic needs of life.

Individuals develop variations either due to mutations or recombinations of genes.

Population becomes heterogenous.

Natural selection operates on this heterogeneity.

This favours speciation by differential and faster reproduction of individuals with variations.

It indicates that Evolution and Natural selection are consequences of some other processes.