Question

With the help of an example, explain how variation leads to evolution.

Answer 1

If one of the progeny is tall (having long legs) than the other progeny. Thus, there may be a variation of height in the progeny.

Now, the advantage of long legs to the progeny is that when no food (grass, etc.) is available on the ground, then this progeny having long legs can reach the leaves on tall trees, eat them as food and survive.

On the other hand, the progeny which have short height (due to short legs) cannot reach the leaves on tall trees, they will not get any food, they will starve.

For example, it is believed that long necked giraffe is evolved from short grass eating animals. Long neck helped them to reach tall tress when there was shortage of grass vegetation.