Q20

[aerokfohp]

Dear Manhattanlsat,

I'm having problems understanding why the answer to Q20 is B.

I first chose E and I don't understand why E is incorrect either.

I got the other questions right but I just don't see the connection between this question and the passage.

Could anyone please help?

Thank you very much.

[farhadshekib]

Hey, I am not a tutor, but I wrote up an explanation for you.


(A) The author does not discuss which theory he finds the "least plausible"; rather, the author simply suggests that the regional speciation theory is the most promising. This response is incorrect.

(B) Indeed, the rate of speciation hypothesis does address a principal objection to the climate stability hypothesis.

In the climate stability hypothesis, "the ecology of local communities cannot account for the origin of the latitudinal gradient" (Line 35).

In contrast, the regional speciation hypothesis suggests that "if speciation rates become higher toward the tropics, and are not negated by extinction rates, then the latitudinal gradient would result _ and become increasingly steep" (Lines 45-50).

(C) We cannot infer what the "major objection" to time theory is based on the information given in the second P. And notice how this A/C tries to, erroneously, combine P1 and P2.

(D) Species energy theory only mentions that high production rates can exist with low biomass, and high biomass can exist with few species. So, this answer choice is beyond the scope of the argument.

(E) This theory does not consider the regional context over the local context to explain the latitudinal gradient.

In fact, I think it may use both (lines 50-55): "most new animal species, and perhaps plants species, arise because a population subgroup becomes isolated (i.e. arise locally). This subgroup evolves differently...The uneven spread of a species over a large geographic area (i.e. different regions) promotes this mechanism: at the edges, small populations spread out and form isolated groups"

Hope this helps

[ManhattanPrepLSAT1]

Nice work farhadshekib!

You're explanation on this one is great!

[bigtree65]

Im still completely lost on this one.

The problem with the climatic-stability hypothesis is that it addresses the local ecology and the the speciation hypothesis addresses this issue by talking about regional effects. This is also exactly what E says about the speciation hypothesis so if B is right how is E wrong?

Someone please help lol

[jackie8848]

I still don't get why B is the correct answer. I think line 35 is the objection to the climate-stability hypothesis, not the hypothesis itself. In fact, the climate-stability hypothesis advocates that the ecology of the local communities does account for the origin of the latitudinal gradient. And the rate-of-speciation seems to be consistent with it. Somebody help me out, please!

[ManhattanPrepLSAT1]

I think line 35 is the objection to the climate-stability hypothesis, not the hypothesis itself.

That is correct. Lines 34-35 outline a problem with the climatic stability hypothesis (that it the climatica stability hypothesis cannot account for the origin of the latitudinal gradient). The author states that the rate-of-speciation hypothesis addresses this problem in lines 44-48 (the latitudinal gradient would be explained).

In fact, the climate-stability hypothesis advocates that the ecology of the local communities does account for the origin of the latitudinal gradient.

Where do you see this? Lines 44-48, where the author does say that the latitudinal gradient can be accounted for, are discussing the rate-of-speciation hypothesis.

The rate-of-speciation hypothesis does account for something that the climatic stability hypothesis cannot account for, and so answer choice (B) looks really good to me.

Lets look at the incorrect answers:

(A) is unsupported. While the author does say that the rate-of-speciation hypothesis is the most plausible, the author never states which is theory is the least plausible.
(C) is contradicted. The problem of species-energy hypothesis is that it's mechanism is untested. The issue of the latitudinal gradient is an issue associated with the climatic stability hypothesis.
(D) is unsupported, the author never makes this claim.
(E) is unsupported. While we do know that the rate-of-speciation hypothesis focuses on regional speciation, but we are not told that this represents an important advantage of the hypothesis compared to others. The important advantage is that it can account for the latitudinal gradient that the climatic stability hypothesis cannot.

Hope that helps!

[niohelang]

I am still lost on this problem. what is climate-stability hypothesis after all? and in what way does the rate-of-speciation addresses an objection? what is the objection?
Can anybody plz explain it clearer?

[cwolfington]

I also picked E at first. But E states that the speciation theory discusses "competition". In the passage, the speciation theory only claims that "subgroups in an arctic environment are more likely to face extinction", and says nothing about "competition"

To fully understand B, read lines 34-48. The author explains the problem with the climatic-stability theory, then shows how the speciation theory "addresses" it.

[Mab6q]

I think line 35 is the objection to the climate-stability hypothesis, not the hypothesis itself.

That is correct. Lines 34-35 outline a problem with the climatic stability hypothesis (that it the climatica stability hypothesis cannot account for the origin of the latitudinal gradient). The author states that the rate-of-speciation hypothesis addresses this problem in lines 44-48 (the latitudinal gradient would be explained).

In fact, the climate-stability hypothesis advocates that the ecology of the local communities does account for the origin of the latitudinal gradient.

Where do you see this? Lines 44-48, where the author does say that the latitudinal gradient can be accounted for, are discussing the rate-of-speciation hypothesis.

The rate-of-speciation hypothesis does account for something that the climatic stability hypothesis cannot account for, and so answer choice (B) looks really good to me.

Lets look at the incorrect answers:

(A) is unsupported. While the author does say that the rate-of-speciation hypothesis is the most plausible, the author never states which is theory is the least plausible.
(C) is contradicted. The problem of species-energy hypothesis is that it's mechanism is untested. The issue of the latitudinal gradient is an issue associated with the climatic stability hypothesis.
(D) is unsupported, the author never makes this claim.
(E) is unsupported. While we do know that the rate-of-speciation hypothesis focuses on regional speciation, but we are not told that this represents an important advantage of the hypothesis compared to others. The important advantage is that it can account for the latitudinal gradient that the climatic stability hypothesis cannot. Hope that helps!

Just to clarify, C talks about the time theory. One poster has suggested that it be eliminated because we don't know that it is the major objection. I believe this is bad logic, as the correct answer choice states that the "principal objection" is addressed by the rate-of-speciation theory, but we don't know that it is the principal objection.

I had a hard time eliminating C on my review, and I think it sounds appealing. However if we go back to the time theory, the basic problem with it is that climatic conditions can't explain everything because certain areas in the temperate zones didn't have ice ages and the climate never changed in the artic. It's not a matter of accounting for the degree of the gradient, but latitudinal gradient itself.

[StratosM31]

I think line 35 is the objection to the climate-stability hypothesis, not the hypothesis itself.

That is correct. Lines 34-35 outline a problem with the climatic stability hypothesis (that it the climatica stability hypothesis cannot account for the origin of the latitudinal gradient). The author states that the rate-of-speciation hypothesis addresses this problem in lines 44-48 (the latitudinal gradient would be explained).

In fact, the climate-stability hypothesis advocates that the ecology of the local communities does account for the origin of the latitudinal gradient.

Where do you see this? Lines 44-48, where the author does say that the latitudinal gradient can be accounted for, are discussing the rate-of-speciation hypothesis.

The rate-of-speciation hypothesis does account for something that the climatic stability hypothesis cannot account for, and so answer choice (B) looks really good to me.

Lets look at the incorrect answers:

(A) is unsupported. While the author does say that the rate-of-speciation hypothesis is the most plausible, the author never states which is theory is the least plausible.
(C) is contradicted. The problem of species-energy hypothesis is that it's mechanism is untested. The issue of the latitudinal gradient is an issue associated with the climatic stability hypothesis.
(D) is unsupported, the author never makes this claim.
(E) is unsupported. While we do know that the rate-of-speciation hypothesis focuses on regional speciation, but we are not told that this represents an important advantage of the hypothesis compared to others. The important advantage is that it can account for the latitudinal gradient that the climatic stability hypothesis cannot. Hope that helps!

Just to clarify, C talks about the time theory. One poster has suggested that it be eliminated because we don't know that it is the major objection. I believe this is bad logic, as the correct answer choice states that the "principal objection" is addressed by the rate-of-speciation theory, but we don't know that it is the principal objection.

I had a hard time eliminating C on my review, and I think it sounds appealing. However if we go back to the time theory, the basic problem with it is that climatic conditions can't explain everything because certain areas in the temperate zones didn't have ice ages and the climate never changed in the artic. It's not a matter of accounting for the degree of the gradient, but latitudinal gradient itself.

I also had a very hard time with eliminating C, but I think that what the poster suggested about the fact that we do not know what the major objection is goes to the right direction.

As far as I understand, there are two objections:

1.) Some temperate regions were disrupted by ice ages less intensely than others, which implies that the degree of the latitudal gradient should have been less (= the theory does not accurately reflect it)
2.) The ice ages did not affect the climate in the arctic regions, which would mean that the theory itself does not make sense at all (the species in the arctic zones had a similar amount of time to adapt as in the tropical zones, so why is there a gradient at all?!)

Indeed, we don't know which one of the two is the MAJOR objection, as it is not stated or implied in the passage. If it said ONE objection instead of THE MAJOR, it would be very problematic to eliminate it...