Biology Graphs: Natural Selection
By L Chapman

There are three types of natural selection. Each type of natural selection has very different consequences for the resulting populations. Directional natural selection causes a shift in the population toward the left or right on the graph. Stabilizing natural selection reduces the extremes in the population. Diversifying natural selection ultimately encourages the reduction of the intermediate numbers.
Which of the three selection types would result in black or white snuzzles (represented with "S") but no gray ones?
Which of the three selection types would result in medium colored snuzzle being the most frequent in the population rather than light or dark snuzzles?
Which selection type might ultimately lead to two separate species unable to mate?