While creation and presence of variation | Class 12 Biology Chapter Evolution, Evolution NCERT Solutions

Variation is defined as the differences among the number of species and offspring of the same parents. All the organisms show variation among every character and in all the direction or we can say directionless. And, the heritable genetic change in the genetic material of an organism that gives rise to alternate forms of any gene is known as mutation (by this organisms would able to survive or adapt to the environmental changes). On the other hand, natural selection to describe the process by which organisms with favourable conditions or variation will survive and reproduces at higher rate. An inherited variations which increases the chances of organism’s survival in the particular environment is known as adaptation and who will not adapt the variations among the environment will die. Thus, we can say that environment provides the direction (this selection brings progressive evolution of traits) with respect to adaptations so that more and more organisms fits the best suited environment.