1.the differences in the traits among the individuals of a species is called variation.
2. Due to creation of variations, a species can adjust to the changing environment around it. And this promotes the survival of the species in the changing environment. For eg, the accumulation of 'heat resistance' variation 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 other hand, the bacteria which don't have this variation to withstand heat would not survive under these circumstance and die.