Question

a scientist has been tracking and studying a population of deer in yellowstone national park. he surveys the population every six months. usually, the population is thriving and has a gene pool with a wide variety of traits. but during one six - month period, an event occurred that affected the population, and when the scientist returned, the amount of genetic variation had decreased significantly. which of the following is most likely the event that occurred to change the population?
yellowstone national park expanded its borders.
a population of wolves was introduced into yellowstone national park.
the amount of disease in the deer population decreased.
more grass and shrubs were planted in yellowstone national park.

Explanation:

When a population of wolves (a predator) is introduced, it can cause a bottleneck effect. A bottleneck effect reduces the population size drastically, and as a result, the genetic variation in the remaining population (deer in this case) decreases. Expanding park borders (\( \text{Yellowstone National Park expanded its borders} \)) would likely increase genetic variation as more space can support more diverse interactions. A decrease in disease (\( \text{The amount of disease in the deer population decreased} \)) would allow more deer to survive, potentially increasing genetic variation. Planting more grass and shrubs (\( \text{More grass and shrubs were planted in Yellowstone National Park} \)) is a positive change for the deer's food supply, which is also likely to support a healthy and genetically diverse population.

Answer:

A population of wolves was introduced into Yellowstone National Park.