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Question

Difficulty: MediumStrengthening or Weakening Author Assertions

Passage:
In evolutionary biology, the 'island rule' posits that large terrestrial mammal species evolving on isolated islands tend to dwarf over time due to resource limitations, whereas small mammal species undergo gigantism due to reduced predation pressure. Paleontologists examining fossil deposits of the extinct insular rodent Canariomys bravoi on Tenerife observed a 40% increase in body mass compared to its mainland ancestors over a 200,000-year period. The researchers asserted that this body mass increase was primarily driven by the absence of terrestrial predators on the island.

Statement: Discovering abundant fossilized remains of an extinct giant raptor on Tenerife that preyed extensively on large rodents during that same 200,000-year period would weaken the researchers' assertion.

Is the statement above True or False?

Answer: Answer

Answer

True
The statement correctly identifies that the discovery of an active predator undermines the researchers' assertion. The researchers attribute the rodent's gigantism specifically to the absence of predation pressure. Demonstrating that an abundant predator hunted these rodents during the exact evolutionary window undermines the assumed absence of predators, weakening the causal claim.

Step-by-Step Solution

1
Identify the author's core assertion and underlying premises.
The researchers claim that the 40% increase in body mass of Canariomys bravoi was primarily driven by the absence of terrestrial predators.
To evaluate a strengthening or weakening statement, one must clear isolate the specific causal claim being made in the text.
2
Analyze the potential impact of the new finding presented in the statement.
The statement introduces evidence of a giant raptor on the island that preyed heavily on large rodents during the same 200,000-year era.
New evidence introducing an active, dedicated predator shows that predation pressure was present and significant during the period of gigantism.
3
Determine whether the new evidence strengthens or weakens the assertion.
Since the assertion relies on the absence of predation as the primary cause, proof of strong predation pressure directly weakens the claim.
Countering the key premise of an argument invalidates the proposed causal mechanism.

Key Concept

Strengthening or Weakening Author Assertions
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Strengthening or Weakening Author Assertions

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