A warthog with the dominant allele, for brown fur color, reproduces with a warthog that has the recessive allele for the white fur. They overproduce because life in the Sahara is rough, so they know that not all of their offspring will survive due to predators.
#3- Natural Selection
The two warthogs overproduced and made variation in their offspring, being that one of them had the recessive gene for the white fur. Now there are a lots of each color warthog babies.
#4- Adaptation of Species
A pride of lions lives nearby and they see the group of warthogs. They see that the brown warthogs are much more appealing in taste to them, so they purposefully hunt down the brown warthogs.
The White Colored Warthogs Thrive
The lions were more attracted to the brown colored warthogs and end up eating those ones instead of the white ones because the brown ones look more tasty. The warthogs develop a structural adaptation, being that their fur changes color throughout time.
The warthogs are now all white in color now, but they still carry the dominant allele for the brown color, so the brown colored fur does not disappear from their gene pool forever. There are just less of the brown furred warthogs.
The white warthogs thrive because they only wanted to eat the brown warthogs, so they move on to eating other prey instead. This leaves the white warthogs to keep on reproducing.