The Galápagos finches studied by Charles Darwin displayed remarkable variation in beak shape and size across different islands, with each...
GMAT Information and Ideas : (Ideas) Questions
The Galápagos finches studied by Charles Darwin displayed remarkable variation in beak shape and size across different islands, with each population showing adaptations suited to local food sources. However, despite their obvious physical differences, genetic analysis reveals that all finch species share common ancestry and maintain similar core DNA sequences. The fundamental genetic similarity among these diverse populations suggests that even significant physical variations ______
Which choice most logically completes the text?
result from environmental pressures rather than genetic changes.
do not necessarily indicate distant evolutionary relationships.
can emerge rapidly within closely related species.
reflect adaptive responses to competitive pressures.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'The Galápagos finches studied by Charles Darwin displayed remarkable variation in beak shape and size across different islands, with each population showing adaptations suited to local food sources.' |
|
| 'However, despite their obvious physical differences, genetic analysis reveals that all finch species share common ancestry and maintain similar core DNA sequences.' |
|
| 'The fundamental genetic similarity among these diverse populations suggests that even significant physical variations ______' |
|
Provide Passage Architecture and Core Elements
Visual Structure Map:
[OBSERVATION: Physical variation in finches] → [CONTRAST: BUT genetic similarity despite differences] → [IMPLICATION: What this suggests about physical variation - MISSING]
Main Point: Despite obvious physical differences, Galápagos finches share common genetic ancestry, suggesting that significant physical variations don't necessarily indicate distant evolutionary relationships.
Argument Flow: The passage opens by establishing the remarkable physical diversity among Darwin's finches across islands. It then contrasts this with genetic evidence showing these diverse populations share common ancestry and similar DNA. This sets up a conclusion about what genetic similarity tells us about the meaning of physical variation.
Step 2: Interpret the Question Precisely
What's being asked? We need to complete the logical conclusion about what genetic similarity suggests regarding physical variations.
What type of answer do we need? A statement that logically follows from the contrast between physical diversity and genetic similarity.
Any limiting keywords? 'Most logically completes' means we need the answer that best fits the logical flow of the argument.
Step 3: Prethink the Answer
- The passage establishes a clear contrast: finches look very different physically but are genetically similar
- The right answer should acknowledge that physical differences and genetic relationships don't always correlate
- The right answer should reflect that genetic similarity can exist despite physical variation
- The right answer should complete the logical implication that shared ancestry suggests physical differences don't necessarily mean evolutionary distance
result from environmental pressures rather than genetic changes.
- Suggests variations result from environmental rather than genetic causes
- Doesn't complete the logical flow about what genetic similarity suggests
do not necessarily indicate distant evolutionary relationships.
- Directly addresses the relationship between physical variation and evolutionary relationships
- Matches our prethinking: genetic similarity suggests physical differences don't necessarily indicate evolutionary distance
can emerge rapidly within closely related species.
- Focuses on speed of emergence rather than evolutionary relationships
- Doesn't address the core implication about genetic similarity vs physical differences
reflect adaptive responses to competitive pressures.
- Introduces competitive pressures not mentioned in the passage
- Doesn't complete the logical connection between genetic similarity and what it suggests about physical variation