All the variations in a species do not have equal chances of survival. Why?

(N/A) Variations are differences in the characteristics of individuals within a species.
Some variations provide a survival advantage to an organism in a specific environment,while others may be neutral or disadvantageous.
Natural selection acts on these variations; individuals with beneficial variations are more likely to survive and reproduce,passing those traits to the next generation.
Since not all variations are equally beneficial for survival in a changing environment,they do not have equal chances of survival.