Question

Why variations are beneficial for species but not necessarily for individual?

Answer 1

Variations are the changes caused in the genetic material thereby bringing about changes in the offspring. Variations caused by mutations can be beneficial or detrimental.
Variations are advantageous to species as the changes which are acquired by variations are inherited by the offspring and certain alterations occur over many generations to make the changes acquired by variations perfect.
Variations may prove to be advantageous or disadvantageous to the individual as the life span of the individual is so small. Variations acquired by the individual are not easily acceptable. Individual with variations is not easily accepted into the group.