There is a genetic Variation in this picture. There are both tan mice and black mice in the dessert grounds, One being the tan mice which is for and the black miceis against.
Overproduction and the struggle for existence: Both mice reproduced and had offsprings and they will continue to have offsprings, but the environment can handle. Not all ofsprings will survive. They will not survive because predators will kill them
Differential survival and reproduction: The tan mice are able to survive because they blend in but the black mice don't blend in so they are eaten by predators.
Changes in gene pool: The tan mice survive and reproduced and flooded the gene pool with the same genes. There was a mutation for one of the mice to be black.