On Pacific islands, a newly arrived gecko species, the house gecko, is displacing the previously established mourning gecko in urban...
GMAT Critical Reasoning : (CR) Questions
On Pacific islands, a newly arrived gecko species, the house gecko, is displacing the previously established mourning gecko in urban areas, but populations of the two species are more stable in rural areas far from human settlement. The house gecko does not attack the mourning gecko, but in areas where insects congregate it prevents the mourning gecko from feeding on them.
Which of the following contributes most to an explanation of the difference between gecko populations in urban and rural areas?
Passage Analysis:
| Text from Passage | Analysis |
|---|---|
| On Pacific islands, a newly arrived gecko species, the house gecko, is displacing the previously established mourning gecko in urban areas, but populations of the two species are more stable in rural areas far from human settlement. |
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| The house gecko does not attack the mourning gecko, but in areas where insects congregate it prevents the mourning gecko from feeding on them. |
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Argument Flow:
The passage starts by presenting an interesting pattern - house geckos are displacing mourning geckos in urban areas but not in rural areas. Then it explains the mechanism behind this displacement - it's not through direct aggression but through competition for food sources where insects gather.
Main Conclusion:
There is no explicit conclusion in this passage. Instead, it presents factual observations about gecko population patterns and the competitive mechanism between the two species.
Logical Structure:
This is actually a setup passage that provides background information rather than making an argument. The first statement establishes the phenomenon (urban vs rural population differences), and the second statement provides the causal mechanism (food competition rather than direct conflict). We're likely expected to use this information to evaluate answer choices that might explain why this pattern differs between urban and rural areas.
Prethinking:
Question type:
Paradox - We need to explain why house geckos displace mourning geckos in urban areas but both species remain stable in rural areas, given that the mechanism is competition for insects where they congregate.
Precision of Claims
The claims are about location-specific population dynamics (urban vs rural), species interaction patterns (displacement vs stability), and feeding behavior (blocking access to insects where they congregate).
Strategy
Since this is a paradox question, we need to find what differs between urban and rural environments that would explain why the same competitive mechanism (house geckos blocking mourning geckos from insects) works differently in these two settings. We should look for factors that would make insect congregation patterns, gecko competition, or feeding dynamics vary between urban and rural areas.