Darwin while evolving the concept of natural selection laid emphasis on competition among individuals belonging to a species, that is intraspecific competition. Here the individuals compete for almost identical requirements from the environment. Competition between individuals belonging to different species, that is interspecific competition is also observed in nature. In the following subsection we shall discuss the essential differences between the two types of competition, and subsequently highlight the role of natural selection in evolving coadapted colnmunities of closely related species.