Due to the creation of variations, a species can adjust can adjust to the changing environment around it . And this promotes the survival of the species in the changing environment . For example, 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. On the hand , the bacteria which did not have this variation to withstand heat would not survive under these circumstances and die.
