In the early 20th century, biologists debated the primary mechanism driving evolutionary change. One school of thought, led by geneticists...
GMAT Information and Ideas : (Ideas) Questions
In the early 20th century, biologists debated the primary mechanism driving evolutionary change. One school of thought, led by geneticists like Thomas Hunt Morgan, emphasized that random genetic mutations were the main source of evolutionary variation. A competing perspective, championed by researchers such as Alfred Russel Wallace, maintained that environmental pressures and adaptive responses to changing conditions were the fundamental drivers of species modification over time.
Which finding, if true, would most directly support Wallace's perspective?
Recent studies show that most evolutionary changes in island populations occurred during periods of significant environmental upheaval.
Genetic analysis reveals that many species share identical mutation patterns across different geographic regions.
Laboratory experiments demonstrate that controlled mutations can produce the same traits found in natural populations.
DNA sequencing shows that closely related species have nearly identical genetic sequences.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'In the early 20th century, biologists debated the primary mechanism driving evolutionary change.' |
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| 'One school of thought, led by geneticists like Thomas Hunt Morgan, emphasized that random genetic mutations were the main source of evolutionary variation.' |
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| 'A competing perspective, championed by researchers such as Alfred Russel Wallace, maintained that environmental pressures and adaptive responses to changing conditions were the fundamental drivers of species modification over time.' |
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Provide Passage Architecture & Core Elements
Main Point: Biologists in the early 20th century held competing views about whether genetic mutations or environmental pressures were the primary drivers of evolutionary change.
Argument Flow: The passage establishes a historical scientific debate, then presents two contrasting perspectives - Morgan's genetics-focused view emphasizing random mutations, versus Wallace's environment-focused view emphasizing adaptive responses to changing conditions.
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- Wallace's perspective centers on environmental pressures and adaptive responses as the fundamental drivers of species modification
- The correct answer should:
- Show evidence that environmental changes trigger evolutionary changes
- Demonstrate that species adapt in response to environmental conditions
- Connect environmental pressures directly to evolutionary modifications
Recent studies show that most evolutionary changes in island populations occurred during periods of significant environmental upheaval.
✓ Correct
- Shows evolutionary changes occurred specifically during environmental upheaval periods
- Directly supports Wallace's claim that environmental pressures drive species modification
Genetic analysis reveals that many species share identical mutation patterns across different geographic regions.
✗ Incorrect
- Focuses on identical mutation patterns across regions
- Supports Morgan's genetic mutation perspective, not Wallace's environmental view
Laboratory experiments demonstrate that controlled mutations can produce the same traits found in natural populations.
✗ Incorrect
- Demonstrates that controlled mutations produce natural traits
- Directly supports Morgan's mutation-centered view
DNA sequencing shows that closely related species have nearly identical genetic sequences.
✗ Incorrect
- Shows genetic similarities between related species
- Focuses on genetic sequences rather than environmental factors