To determine which explanation is best supported by the numbers in the chart, let's analyze the population changes of the animals mentioned.
1. Cheetah Population Change:
- In 1990, the cheetah population was 100,000.
- In 2000, the cheetah population was 47,000.
- Change in cheetah population = 47,000 - 100,000 = -53,000.
2. Zebra Population Change:
- In 1990, the zebra population was 50,000.
- In 2000, the zebra population was 7,500.
- Change in zebra population = 7,500 - 50,000 = -42,500.
These values indicate that both the cheetah and zebra populations declined between 1990 and 2000.
Based on the explanation options:
1. Lion and cheetah populations compete for the food source of zebras, and lions outcompete cheetahs:
- This statement is not supported by the given data as there is no specific information on lion populations in 1990 and 2000.
2. The dwindling zebra population has led to the decline of the predator lion and cheetah populations:
- This explanation is supported by the numbers. The decline in the zebra population could logically lead to a reduction in available food for predators like cheetahs (and likely lions if their data were provided), causing their populations to also decline.
3. Overhunting of lion and cheetah populations has led to a decline in the food source population:
- There is no data about the population sizes of lions, and overhunting of cheetahs leading to a decline in zebra populations is not a logical cause-and-effect relationship. Predators being hunted would not directly lead to a decline in their prey population.
Given the data, the best-supported explanation is:
The dwindling zebra population has led to the decline of the predator lion and cheetah populations. The significant decreases in both predator and prey populations suggest this causal relationship.
