How does natural selection change the frequency of genes or traits over many generations? Biology students conducted an experiment mimicking genetic variation and coloration. Students used different colored beans to represent animals that might be prey: mice, for example. A student in each group was the predator: a hawk. Beans (mice) were randomly scattered on multicolored floor tiles, each color within four tiles. The hawk collected mice (beans) for 10 seconds. Mice not eaten reproduced. Three generations of data is shown in the table. All BUT ONE could be a reason for the color variation in the mice. That is .