Conservationists have begun removing plant species believed to be nonnative, or introduced through human contact, from the Galápagos Islands to...

GMAT Critical Reasoning : (CR) Questions

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Conservationists have begun removing plant species believed to be nonnative, or introduced through human contact, from the Galápagos Islands to restore the islands' ecosystem. But some of these species may be native after all. Humans first reached the Galápagos in 1535, but fossilized pollen grains of several species thought to be nonnative were found in sediment cores over 8,000 years old. Among these species is swamp hibiscus. This plant is spreading, which was taken as evidence of its invasiveness, but scientists now hypothesize that it is reclaiming habitat that was lost over time.

Which of the following would it be most useful to establish in order to evaluate the scientists' hypothesis that swamp hibiscus is reclaiming habitat?

Whether swamp hibiscus provides food for any animal species native to the Galápagos

Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos

Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated

Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources

Whether fossilized plant leaves have also been found on the Galápagos

Solution

Passage Analysis:

Text from Passage	Analysis
Conservationists have begun removing plant species believed to be nonnative, or introduced through human contact, from the Galápagos Islands to restore the islands' ecosystem.	What it says: Conservationists are removing plants they think don't belong naturally on the Galápagos Islands What it does: Sets up the context - shows us what's currently happening with conservation efforts What it is: Background information about current conservation practices
But some of these species may be native after all.	What it says: The plants being removed might actually belong there naturally What it does: Creates a twist - challenges what we just learned about the conservation efforts What it is: Author's claim that contradicts the conservationists' assumption
Humans first reached the Galápagos in 1535, but fossilized pollen grains of several species thought to be nonnative were found in sediment cores over 8,000 years old.	What it says: People arrived in 1535, but plant evidence shows some "nonnative" species were there 8,000+ years ago What it does: Provides concrete evidence supporting the previous claim that some species might be native What it is: Scientific evidence from fossil records Visualization: Timeline: 8,000+ years ago (plants present) ←——————→ 1535 (humans arrive)
Among these species is swamp hibiscus.	What it says: Swamp hibiscus is one of the plants found in those ancient fossils What it does: Focuses our attention on one specific example from the broader evidence What it is: Specific example of the fossil evidence
This plant is spreading, which was taken as evidence of its invasiveness, but scientists now hypothesize that it is reclaiming habitat that was lost over time.	What it says: Swamp hibiscus is spreading, but scientists think it's returning to areas where it used to grow naturally What it does: Presents two competing explanations for the same observation (spreading behavior) What it is: Scientists' new hypothesis versus old interpretation

Argument Flow:

The argument starts with current conservation practices, then challenges those practices with fossil evidence, and finally focuses on a specific case (swamp hibiscus) where scientists are reconsidering their interpretation of plant behavior.

Main Conclusion:

There isn't a single main conclusion here - this is more of an informational passage explaining competing hypotheses about whether swamp hibiscus is invasive or native.

Logical Structure:

The passage uses chronological evidence (8,000-year-old fossils vs. 1535 human arrival) to support the idea that some "nonnative" species might actually be native, then presents scientists' new hypothesis about swamp hibiscus as a specific example of this broader possibility.

Prethinking:

Question type:

Evaluate - We need to find what information would help us test whether the scientists' hypothesis about swamp hibiscus reclaiming lost habitat is correct or not

Precision of Claims

The key claim is about activity/behavior - that swamp hibiscus is 'reclaiming habitat that was lost over time' rather than being invasive. This is a specific claim about the nature and cause of the plant's spreading pattern

Strategy

For evaluate questions, we need to think of what assumptions the scientists are making about swamp hibiscus reclaiming habitat. Then we create scenarios that would either strongly support or strongly contradict this hypothesis when we get evidence one way or the other. The best evaluation criterion will be something that clearly distinguishes between 'reclaiming old habitat' versus 'invasively spreading to new areas'

Answer Choices Explained

Whether swamp hibiscus provides food for any animal species native to the Galápagos

Whether swamp hibiscus provides food for native animals doesn't help us evaluate whether the plant is reclaiming habitat versus being invasive. This information tells us about ecological relationships but doesn't distinguish between the two competing explanations for the plant's spreading behavior. The scientists' hypothesis is specifically about the nature of the spreading pattern, not about the plant's role in the food web.

Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos

Whether swamp hibiscus found elsewhere is related to Galápagos swamp hibiscus doesn't help evaluate the reclaiming habitat hypothesis. This would tell us about genetic relationships between plant populations, but it doesn't address whether the current spreading represents habitat reclamation or invasive behavior. The fossil evidence already suggests the plant was present 8,000+ years ago, so genetic relationships with other populations don't clarify the spreading pattern.

Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated

Whether swamp hibiscus is native to areas where the first humans originated is irrelevant to evaluating the habitat reclamation hypothesis. We already know from fossil evidence that the plant was on the Galápagos 8,000+ years ago, well before human arrival in 1535. Information about the plant's presence in human origin areas doesn't help us understand whether current spreading represents reclaiming old habitat or invasive expansion.

Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources

This is exactly what we need to evaluate the hypothesis. If nonnative plants recently removed from the Galápagos were competing against swamp hibiscus for resources, this would strongly support the scientists' hypothesis. Removing competitors would naturally allow swamp hibiscus to expand back into areas where it was previously suppressed - perfectly explaining the spreading as 'reclaiming habitat.' If no such competition existed, it would be much harder to explain the spreading as habitat reclamation rather than invasive behavior.

Whether fossilized plant leaves have also been found on the Galápagos

Whether fossilized plant leaves have been found doesn't help evaluate the specific hypothesis about swamp hibiscus reclaiming habitat. We already have fossil pollen evidence showing the plant's ancient presence. Additional fossil evidence wouldn't clarify whether current spreading represents habitat reclamation or invasive expansion - the key distinction we need to evaluate.

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