You Conduct an Experiment in Which You Raise Six Replicated

You conduct an experiment in which you raise six replicated lines of fruit flies for eight generations. You keep population size constant at 20 adults per generation. You are interested in a gene, bw, that affects eye color. This gene has two alleles, bw-1 and bw-2. You start each replicated line with the frequency of the bw-1 allele at 50 percent. Do the data in the graph better match the prediction for the bw alleles evolving by genetic drift or by directional selection? Be sure to define directional selection and genetic drift and describe the prediction of both hypotheses.