The Hedgehogs with the dominant allele, in this case the hedgehogs with sharp quills (dark brown) reproduces with a dull quill hedgehog (light brown) who carries the recessive gene. The hedgehogs know that there are predator in the forest in which they live, so the have many offspring to ensure their species wont die out.
The hedgehogs overproduced and because of this, there is now more variation in the species of hedgehogs. About half of them have sharp quills like one of their parents while the other have dull quills like the other parent. This tells us that the dominant allele appeared in about half of the hedgehog offspring.
A scheming parliament of owls now lurks in the shadows of the forest. Not only can can the owls the light colored hedgehogs better, but have also learned that they have less defense due to the fact that they have dull quills.
Because the dull quilled hedgehogs are easier targets, the population of this version of hedgehog begins to decrease, while the sharp quilled hedgehog numbers are increasing.
The population of hedgehogs is now prominently dark brown with sharp quills. Despite this, there are still a small number of light colored hedgehogs, and the dark colored ones do still hold the recessive gene that creates the dull quilled hog. It basically just means there is a much less chance of the hedgehogs offspring inheriting the dull quill trait.
In conclusion the sharp quilled hedgehogs are now in a state where they thrive because their predators (the owls) have less effective tactics in order to consume the hedgehogs, leading them to find a different source of food. (Sorry little mice!!)