Gray mice are less visible to hawks that fly overhead and feed on mice Over time many homozygous black and white mice are eaten while the heterozygous gray ones survive and reproduce What is this a?

This would be survival of the fittest and evolution at work. Because the gray mice are harder for the birds to see, they live to reproduce and pass their genes for color on. This is why most wild mice are gray in color, while domesticated mice are a variety of colors. Domesticated mice were bred to be pretty, while the wild mice breed for survival.