There are to types of rabbits that live in the savanna. One has dark brown fur and tends to stand out more than the other beige colored fur which allows it to blend well with the grass.
Rabbits can have up to 14 offspring (babies) but are usually they prey of coyotes, hawks, leopards, dingoes and many more which caused there population to be at risk depending on the offspring made and whether or not they have mutations that are beneficial or not.
Because the darker brown fur stands out more than the beige one, they are more likely to get eaten by predators and will not able to pass on its genes to future generations. The only way to get another darker brown or shade of fur is if the other beige get mutations.
Due to the predators eating the darker brown rabbits they will decrease over time in the population and the beige rabbits will increase.