A population of pacas, a nocturnal rodent, live in South America. Their diet consists of leaves, flowers, and fruits that have fallen from taller trees. A recent fire has wiped out much of the food that the pacas eat. This has caused the pacas to lose body mass. Due to the lack of food, subsequent generations of pacas are thinner than the preceding generations. Identify if this is an example of descent with modification and justify your response.