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:

To determine the event that reduced genetic variation in the deer population, we analyze each option:

• Expanding park borders (first option) would likely increase habitat, not reduce genetic variation.
• Introducing wolves (second option) would act as a selective pressure, potentially causing a bottleneck effect (reducing population size and thus genetic variation) as wolves prey on deer, removing individuals with certain traits.
• Decreasing disease (third option) would likely increase population health and size, not reduce genetic variation.
• Planting more grass/shrubs (fourth option) provides more resources, supporting population growth, not reducing variation.

The introduction of wolves is the most likely event to cause a significant decrease in genetic variation via a bottleneck or strong selection.

Answer:

B. A population of wolves was introduced into Yellowstone National Park.