Predator-Prey Relationships

Predator-Prey Relationships

Multiple Choice

A new predator is introduced into a forest ecosystem that preys on both rabbits and squirrels. After several years, the rabbit population declines significantly while the squirrel population remains relatively stable. What is the most likely explanation for this pattern?

• The predator prefers to hunt squirrels over rabbits.

• The predator prefers to hunt rabbits over squirrels.

• The predator has an equal preference for hunting both rabbits and squirrels.

• The decline in the rabbit population is unrelated to the presence of the predator.

​Explanation

​The most likely explanation for the observed pattern of the decline in the rabbit population and the stable squirrel population is that the predator introduced into the ecosystem prefers to hunt rabbits over squirrels. We know this because the rabbit population has declined significantly while the squirrel population has remained relatively stable. If the predator had an equal preference for hunting both rabbits and squirrels (answer choice C), we would expect to see a decline in both populations. If the predator preferred to hunt squirrels over rabbits (answer choice A), we would expect to see a decline in the squirrel population and not the rabbit population. If the decline in the rabbit population was unrelated to the presence of the predator (answer choice D), we would not expect to see a significant decline in the rabbit population. Therefore, answer choice B, "The predator prefers to hunt rabbits over squirrels," is the best explanation for the observed pattern. This demonstrates how predator-prey relationships can affect populations in an ecosystem.

Multiple Choice

A new predator is introduced into a meadow ecosystem that preys on both orange and blue butterflies. After several years, the orange butterfly population declines significantly while the blue butterfly population remains relatively stable. A biologist observes that the predator is more easily able to see the orange butterflies in the meadow due to their bright coloration. Based on the data in the table below, what is the most likely explanation for this pattern?

• The predator prefers to hunt blue butterflies over orange butterflies.

• The predator prefers to hunt orange butterflies over blue butterflies.

• The predator has an equal preference for hunting both orange and blue butterflies.

• The decline in the orange butterfly population is unrelated to the presence of the predator.

​Explanation

The data in the table shows that the orange butterfly population has declined significantly while the blue butterfly population remains relatively stable. The most likely explanation for this pattern is that the predator introduced into the meadow ecosystem prefers to hunt orange butterflies over blue butterflies. We know this because the orange butterfly population has declined significantly while the blue butterfly population remains relatively stable, indicating that the predator is not hunting blue butterflies as much. Additionally, the biologist's observation that the predator is more easily able to see the orange butterflies due to their bright coloration supports this explanation. Answer choices A and C are less likely to be correct because they suggest that the predator has no preference or a preference for blue butterflies, which does not explain the observed decline in the orange butterfly population. Answer choice D suggests that the decline in the orange butterfly population is unrelated to the predator, which is unlikely given the observation that the predator is more easily able to see the orange butterflies due to their bright coloration. Therefore, answer choice B, "The predator prefers to hunt orange butterflies over blue butterflies," is the best explanation for the observed pattern. This demonstrates how selective pressures can influence the evolution of coloration in animals and how predator-prey relationships can affect populations in an ecosystem.

Multiple Choice

In a forest ecosystem, the population of wolves has increased significantly over the past decade, leading to a decrease in the population of moose. A biologist hypothesizes that the increase in the wolf population has led to a decrease in the moose population. Which of the following observations would best support this hypothesis?

• The moose population has decreased due to disease.

• The wolf population has decreased due to hunting.

• The wolf population has increased due to a decrease in the population of deer, which has led to an increase in the population of plants that the moose eat.

• The moose population has decreased due to an increase in the number of predators that also prey on moose, such as bears and cougars.

​Explanation

The hypothesis is that the increase in the wolf population has led to a decrease in the moose population. The observation that best supports this hypothesis is that the moose population has decreased due to an increase in the number of predators that also prey on moose, such as bears and cougars. If there are more predators overall that prey on moose, then it is more likely that the increase in the wolf population has contributed to the decrease in the moose population. Answer choices A, B, and C are less likely to be correct because they do not address the relationship between the wolf and moose populations directly. Answer choice D, "The moose population has decreased due to an increase in the number of predators that also prey on moose, such as bears and cougars," is the best observation to support the hypothesis. This question shows how changes in the population of one species can impact the population of another species in an ecosystem, and highlights the complex relationships that exist within ecosystems.