PT19.S3.Q18 - When the same habitat types

Henry An

Hello,

I have a question on a reading comprehension question (PT 19 S3 Q18). I was really shocked to see that the answer was E. While testing, I thought this was a typical trap answer choice used in weakening questions on logical reasoning, and I can't seem to understand why this is the answer. With respect to the rate-of-speciation hypothesis, the author of the passage compares the arctic and tropics, stating that the "subgroups in an arctic environment are more likely to face extinction than those in the tropics," and that "the latter are more likely to survive long enough to adapt." (lines 57 - 61)

On the other hand, answer choice E states that "most of the isolated subgroups of mammalian life within a tropical zone are found to experience rapid extinction." In assessing this, I thought this had no bearing on weakening the argument made in the passage because it did not compare between the arctics and tropics. Who cares if "most" of the life in the tropics experience rapid extinction? I thought:

(1) most? if there were 100 million subgroups, and only 20 million survived, who is to say that this is not enough to create a new species?

(2) the rate-of-speciation hypothesis is in regards to the rate of speciation compared to that of extinction (lines 45 - 48). Even if there is a high rate of extinction, if there is a higher rate of speciation compared to that of extinction, the hypothesis would still hold

and

(3) as this answer choice does not compare arctics to tropics, who is to say that the arctics do not have an even more rapid rate of extinction? Therefore, there a more species in the tropics than the arctic.

Is there something that I'm missing? The only reason I can think of to why the answer is E is just that it is just the best out of the bunch. Still, I would like to think that if such a question were to appear on a logical reasoning question, it would be a wrong answer choice... Any help would be great with this question!

https://7sage.com/lsat_explanations/lsat-19-section-3-passage-3-passage/
https://7sage.com/lsat_explanations/lsat-19-section-3-passage-3-questions/

Sami

So I re-read the last paragraph of the passage to answer this question and I did the question before I attempted to write my reply. I was going to write how I got to answer choice E, but reading your explanation I have to say I cannot find fault with what you wrote.

The passage does say that the subgroups in arctic are more likely to face extinction in the arctic than the tropics. So with answer choice E it seems fine for most species to experience extinction as long as they are more likely to survive than the arctic.

There are two things that I think make answer choice E correct.

1. Like you said, it is a lot better than the other 4 answer choices and in weakening questions we only have to weaken the idea a little bit.

2. Line 45 says, if speciation rates become higher towards the tropics and are not negated by extinction rates then latitudinal gradient would result. This whole theory rests on extinction rates. So if our species in tropics are negated a lot by rapid extinction rates, like answer choice E says, then it would follow that it is possible that the latitudinal gradient might not result. So E weakens our answer choice slightly this way.

I am sorry I wasn't a better help. I think you really brought up an interesting point.

LSATcantwin

I took this test last week and got this answer right. The reason I chose it was because it seemed to respond directly to line 46..... "and are not negated by extinction rates..." AC E shows a negation of extinction rates so I picked it.

Reading your explanation now I'm skeptical. It's even worse than you stated because its only talking about mammalian life. What about reptile/bird/whatever? That makes the number even smaller. 10 species - 4 are mammals 3 die out. we still have 7 species left....and the reptiles can go on making new species to their hearts content....