Accumulation of Variations
The variations produced in organisms during successive generations get accumulated in the organisms. The significance of a variation shows up only if it continues to be inherited by the offspring for several generations.
The great advantage of variation to a species is that it increases the chance of its survival in a changing environment. Such as the accumulation of heat Resistant variation (or trait) in some bacteria will ensure its survival even when the temperature in its environment rises too much due to a heat wave or some other reasons.