LSAT 101 | Section 4 | Reading Comprehension: Q20

RC Question 20 Explanation

DISCUSSION: The “latitudinal gradient” is a fancy way of saying: Habitats closer to the pole have more species.

The author agrees with the fourth theory. They think  it’s easier for new species to survive in the tropics.

___________

1. The author disagrees with theories 1-3. But the author hasn’t said which theory is the most flawed.
2. CORRECT. Step one is to check why the author thinks the climatic-stability hypothesis is wrong. That’s lines 34-35: the theory can’t explain why there are more species in the tropics.
    
   The fourth theory (rate-of-speciation) can explain this fact: new species survive more easily in the tropics.
3. This answer just strings together terms from the passage to form a nonsense answer.
    
   The time theory is only mentioned in paragraph two. It’s a short paragraph. Only one objection is given, and it’s a different objection: some habitats were less affected by ice ages, yet they still have a smaller number of species.
4. Lines 22-24 said that high production rates can exist with low biomass. But the author never said what usually happens.
    
   The point of the author’s criticism was to argue that the correlation probably didn’t indicate causation.
5. This distinction is never made. The author looks at regional speciation rates, and considers whether a species can survive under local conditions (lines 54-56 and lines 59-61). Both regional and local are important.