If the mutation adds a new gene then the change will be found

The next finger is the middle finger. The M in the middle finger should remind you of the M in the word "mutation." If a new gene is added through mutation, it can affect the frequency. Imagine a gene mutation creates a new color of hair. This would obviously change the frequency in the gene pool.
The pointer finger should remind you of movement. If new individuals flow into an area, or immigrate, the frequency will change. If individuals flow out
of an area, or emigrate, then the frequency will change.