To determine the best explanation supported by the numbers in the chart, let's first analyze the changes in the population sizes of the three African animals between 1990 and 2000:
1. Lions:
- 1990: 100,000
- 2000: 47,000
- Decline: \(100,000 - 47,000 = 53,000\)
2. Cheetahs:
- 1990: 50,000
- 2000: 7,500
- Decline: \(50,000 - 7,500 = 42,500\)
3. Zebras:
- 1990: 15,000
- 2000: 2,500
- Decline: \(15,000 - 2,500 = 12,500\)
The analysis shows significant declines in the populations of lions, cheetahs, and zebras over the decade.
Now, let's evaluate the possible explanations:
1. Lion and cheetah populations compete for the food source of zebras, and lions outcompete cheetahs.
- This explanation would involve lions maintaining or increasing their population while cheetah populations decline. However, both populations decreased substantially, suggesting it’s not competition with each other as the primary cause.
2. The dwindling zebra population has led to the decline of the predator lion and cheetah populations.
- This explanation is supported by the data. The significant decline in zebra populations, which are a key prey species, correlates with the declines in predator populations (lions and cheetahs).
3. Overhunting of lion and cheetah populations has led to a decline in the food source population.
- If overhunting of lions and cheetahs were the cause, the prey population (zebras) would likely increase due to less predation pressure. However, zebra numbers have also declined, suggesting this explanation is not supported by the data.
4. Lion and cheetah populations compete for the food source of zebras, and cheetahs outcompete lions.
- Similar to the first explanation, this would involve cheetahs potentially increasing or maintaining their numbers while lion populations decline. The data shows substantial declines in both populations, indicating this explanation is also not supported.
The best-supported explanation by the numbers in the chart is:
The dwindling zebra population has led to the decline of the predator lion and cheetah populations.
Therefore, the analysis leads us to conclude that the declining zebra population has negatively impacted the populations of their predators, lions, and cheetahs.
