#20 - Global Reference, Must Be True, Author's Perspective

[Administrator]

Complete Question Explanation

The correct answer choice is (B).

Answer choice (A):

Answer choice (B): This is the correct answer choice.

Answer choice (C):

Answer choice (D):

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[Johnny_Yeo]

Hello,

Can someone please tell me how B is the answer to the question? Is it because the rate-of-speciation hypothesis deals with regional speciation as opposed to the local focus in the Climatic stability hypothesis?

[Adam Tyson]

You picked a fun one, Johnny!

The short answer here is yes, you hit the nail on the head. B is the best answer because our author would agree that rate-of-speciation addresses the regional differences that the climatic stability hypothesis fails to address.

What a dense passage! I dreaded this one! Nice work.

[jrc3813]

If E did not include the word "competition" would it be correct? The stability hypothesis involves competition but the regional speciation hypothesis doesn't mention it. The problem with the stability hypothesis is that its localized explanations cannot be applied to a regional context and therefore do not explain the origins of the gradient.

[nicholaspavic]

Hi jrc,

I think I follow your argument about the elimination of the word "competition" from Answer Option (E) and I agree that it may have definitely helped cure the answer of its defect. This question is tough in general but (B) and (E) are the main contenders for their positive views on the rate-of-speciation hypothesis. Definitely, the qualification of "competition" in (E) makes this the basis for disqualifying it as the correct choice. So well done!

Thanks for the great input!

[ikim10]

Hello, I'm still not entirely clear on why B is correct over E. Please check my understanding below:

I can see that the primary objection for the climatic-stability theory is that localized ecological processes (like competition) cannot be applied to larger areas like regions, and thus cannot be responsible for the latitudinal gradient.

The rate-of-speciation theory proposes that regional speciation is the most likely candidate responsible for the latitudinal gradient, in that speciation rates grow higher the closer we approach the equator.

The only way I can see how the rate-of-speciation theory addresses a principal objection to the climatic-theory hypothesis is that is accounts for regional speciation, which the climatic-theory hypothesis does not (as in B). But E seemed valid to me as well for the same reason.

I read the above discussion, but I don't see how the word "competition" in E makes it incorrect.

My guess is that E is interpreted more as saying that the two theories are near identical, but just that the rate-of-speciation theory considers processes in a regional context vs local? And that makes it incorrect because the two choices are different?

[Rachael Wilkenfeld]

Hi ikim10,

The rate of speciation argument is not related to completion. It's not about how different species compete for resources. It's about how species can form in isolated areas. As they evolve in isolation, they can no longer interbreed, and thus become a new species. The interesting bit here isn't that the tropics have such an unusual rate of evolution. It's that they have an unusual rate of survival. According to the final paragraph, it's harder to survive in areas toward the poles, so there are fewer opportunities for isolated groups to survive to become new species. It's not about competing, it's about survival. Answer choice (E) incorrectly talks about competition, which is a concept from the third theory, not the final theory.

Hope that helps!

[ikim10]

I narrowed down my answers to (B) and (E). Could you please explain why (B) is correct?

[Stephanie Oswalt]

I narrowed down my answers to (B) and (E). Could you please explain why (B) is correct?

Hi ikim10!

I have moved your post to the thread discussing this topic. Please read the above discussion, particularly Rachael's response right above this, and let us know if this helps! Thanks!