In the preceding block you learnt the Darwinian premise of natural selection based on certain facts and deductions thereof. You would have noticed that one of the foundations for the concept of natural selection relates to competition among the individuals belonging to the same species - the intraspecific competition. You may also recall that intraspecific competition involves two components - (1) the individuals belonging to the same species compete among themselves for thc same requisites from the eilvironment which results in physical competition, including the competition for mates and the individuals belonging to a species may compete as to which of them leaves behind a major share of descendents in the future populations. The second type of competition is more subtle, by which is meant that individuals do not compete directly or in any physical way. The success of the second type of competition is measured in terms of the survival of offsprings, and therefore alleles in the next generation. You might have by now deduced that the two types of competition are interrelated. Success in the first type of competition known as ecological intraspecific competition is a prerequisite for success in the second type of competition namely reproductive intraspecific competition. It does not mean that ecological success always ensures reproductive success, for ecologically successful individuals may be sterile; but ecological success is always necessary to achieve reproductive success. We may then summarise that intraspecific competition results in adaptations to a given environment and this helps to perpetuate the genotypes of successful individuals generation after generation.