Define variations in relation to a species. Why is variation beneficial to the species?

Definition: Variation is differences in structure, physiology and other characters found in the individuals of the same organism.

Benefits of variations to species.

Many of the variations are pre-adaptations which have no immediate benefit to the individuals. However, they remain in the population. Whenever, environment undergoes a drastic change, the pre-adaptations present in some members of the population allow the latter to survive, grow and regain its former size. Therefore, it is not necessary that variations are beneficial to individuals developing them but can prove useful to the species.