Reading Comprehension

PT157 · S4 · P3 · Q19 Definition of Species

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Political arguments about biodiversity and the preservation of endangered species generally assume we know what a species is.

Topic

The challenge and controversy of defining what counts as a "species," especially in ornithology, and the implications of different definitions.

Framework

Present Debate

Main Point

There is an ongoing debate among scientists about how to define a species, with significant practical and political consequences, especially for conservation. ( — opening sentences, and the summary of practical stakes at the end.)

P1: Debate Over What Constitutes a Species

This paragraph introduces the ongoing debate about what a "species" actually is, focusing on the classic divide between "lumpers" (who group similar populations) and "splitters" (who separate populations into more species). Lumpers use the biological species concept (reproductive isolation), while splitters prefer the phylogenetic species concept (diagnosable populations with unique, genetically traceable traits).

P2: Example of a "Splitter" – Sibley's Contributions

Here we get an example in ornithology: Charles G. Sibley, a splitter, used DNA technology to challenge conventional classifications of bird species, arguing for unexpected relationships among birds (like American vultures being closer to storks than to other vultures).

P3: Pushback and the Limits of Classification

Sibley's ideas faced significant criticism. A critic argues that interpreting genetic differences is arbitrary, and even Sibley concedes that species definitions are inherently slippery because many populations don’t fit our tidy definitions.

19.

If valid, Charles G. Sibley's findings, as described in the last two sentences of the second paragraph, most seriously challenge which one of the following assertions?

  1. A stork population from Europe

    Unsupported

    Sibley thinks that American vultures are more closely related to storks than to European vultures, so his findings would agree with this assertion.

    5% picked this

  2. A stork population from South

    Unsupported

    Sibley thinks that American vultures are more closely related to storks than to European vultures, so his findings would agree with this assertion.

    4% picked this

  3. Correct

    A vulture population from North

    Why this is right

    Sibley thinks that American vultures are more closely related to storks than to European vultures, so his findings would go against this assertion. He would expect an American vulture to be related to storks, not to a European vulture.

    Skill tested: Application · how this choice captures the passage's function is the move to repeat next time.

    63% picked this

  4. A vulture population from South

    Unsupported

    Sibley thinks that American vultures are more closely related to storks than to European vultures, so his findings would agree with this assertion. We can see that (B) and (D) would cancel out, since they're the same answer, other than switching North and South America, which were treated equivalently in the passage.

    23% picked this

  5. A vulture population from North

    Unsupported

    Sibley thinks that American vultures are more closely related to storks than to European vultures, so his findings are pretty neutral towards this assertion. To the extent that the passage refers to North and South American vultures as one group, it seems like Sibley thinks North and South American vultures are quite related and would thus presumably agree with this claim.

    6% picked this

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