Answer:
A number of chipmunks die due to old age.
Step-by-step explanation:
A mutation is any genetic change in the genome of an organism. When a mutation occurs in germline cells it may be passed from one generation to the next, thereby changing the gene pool in a population. Moreover, gene flow is the transference of genetic material among populations, which also have the potential to modify the gene pool in a population. Gene flow may be caused by the movement (migration) of individuals from one population to another and further reproduction of these organisms. Both mutations (i.e., germline mutations) and gene flow (i.e., migration) are evolutionary forces capable of changing the gene pool composition of a population. On the other hand, a pesticide that causes the death of many individuals may also potentially alter the gene pool in a population. Finally, old individuals that death by age are not expected to modify the gene pool of a population (since these organisms don't reproduce).