LSAT 101 | Section 4 | Reading Comprehension: Q18

RC Question 18 Explanation

DISCUSSION: Rate-of-speciation is the final theory, from paragraphs five and six. The author agrees with this theory.

The theory claims there has been a higher rate of species growth in the tropics.

New species form when a sub-group of a species can isolate itself and survive long enough to form a new species.

The theory claims that these sub-groups can survive more easily in the tropics than in the arctic.

___________

1. This shows that a new species has formed. This supports the theory.
2. This supports the idea that sub-groups can survive more easily in the tropics.
3. This is tempting, because it sounds like it would support the third hypothesis, the climatic stability hypothesis. If that hypothesis were true, the fourth hypothesis would be wrong.
    
   What’s the problem? This answer says correlation, which was already established. We would need to establish causation to support the third hypothesis.
4. This could mean that researchers find one undiscovered species, instead of none. That wouldn’t mean much.
5. CORRECT. The theory predicts that it’s easier for subgroups to survive in the tropics. This shows that most sub-groups die in the tropics.
   It doesn’t destroy the theory – it’s possible that even more subgroups die up north. But it does slightly weaken the idea that it’s easy for a sub-group to survive in the tropics.