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 decreased the deer population's genetic variation, we analyze each option:

• Expanding park borders (first option) would likely increase habitat and genetic diversity, not decrease it.
• Introducing wolves (second option) would act as a selective pressure, potentially reducing the deer population size (e.g., through predation on certain traits), leading to a bottleneck effect which decreases genetic variation.
• Decreasing disease (third option) would allow the population to thrive and likely increase genetic variation as more individuals survive.
• Planting more grass/shrubs (fourth option) provides more resources, supporting population growth and increased genetic diversity.

The bottleneck effect from wolf introduction best explains the reduced genetic variation.

Answer:

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