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 these is most likely the event that occurred to change the population?
Answer
A
Yellowstone National Park expanded its borders.
B
More grass and shrubs were planted in Yellowstone National Park.
C
A population of wolves was introduced into Yellowstone National Park.
D
The amount of disease in the deer population decreased.
Explanation
Introducing wolves adds a new predator that could sharply reduce the deer population. If many deer are lost, the surviving population may carry only a smaller sample of the original gene pool, decreasing genetic variation. Less disease, a larger park, or more food would not be as likely to cause this sudden loss of variation.
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