A population of rabbits has moved into a new area where the dirt is very dark. according to natural genetic variation , some dark rabbits are brown and the others are tan.
tan rabbits are visible to predatory raccoons than the brown rabbits . so tan mice are eaten at a higher frequency than brown mice. Only the surviving rabbits reach reproductive age and leave offspring.
Because brown mice had a higher chance of leaving offspring than tan mice, the next generation contains a higher fraction of brown rabbits than the previous generation.
Due to the reason why brown rabbits camouflage the tan mice are no only alive in the generation because they we all eaten and weren't able to pass on their offspring.