Variations develop in each species. Only those variations, which are favorable to that nature, survive and those which are unfavorable get eliminated, According to Darwin, organisms of one kind, when produced in large numbers (Over Production), compete for food, space, mate, and other limited resources (Struggle for Existence). In this struggle, only organisms with favorable variations survive in that nature (Survival of the Fittest). Over a long period, the favorable variations accumulate, resulting the formation of new species.
