Short answer: Variations bring about favourable changes in an organism that allow it to survive better than others in the population.
Sometimes there occur changes in the environment that are so drastic that they make survival for certain organisms very difficult.
For example, let us assume that a group of beetles can only survive upto 50 degrees celcius of temperature, but there are few beetles in the population with a variation that allows them to withstand or tolerate higher temperature. So, if the temperature rises all those beetles that could only survive upto 50 degrees of temperature would die off. Those beetles that could tolerate the higher temperature would survive and reproduce.
Note: Keep in mind that not all variations are necessarily useful. It depends on the extrenal environment
Rate this question :