Q7 - Researcher: Over the course of three decades

[hyewonkim89]

I'm not sure why I took so long to solve this question when I was timing myself..

(A) made me hesitate a lot until I got to (C), which seems to explain better why the average beak size of the wild birds decreased - larger beak sized birds were slowly dying out. Also, it wasn't a problem for the captive birds since they were probably fed.

But I want to make sure I eliminated (A) for the right reason.

I think (A) is wrong because it didn't really explain why the captive birds' beak size remained the same. Also, it seemed to go against the premises. The researcher said they kept the records of the average beak size of two populations, but (A) seemed to be catching doubts on the premises.

Does that make sense? Any help would be appreciated!

[tommywallach]

Let's take this on from the beginning:

Weird thing: Captive birds didn't have beak decrease, wild birds did.

(A) This answer doesn't discuss change. This would explain why the captive birds had smaller beaks than the wild birds, but not the change in beak size.

(B) Same as (A)

(C) CORRECT. This provides an explanation for the difference. Birds in captivity had a constant food supply, but the wild birds needed to have smaller beaks, so evolution favored the small-beak birds.

(D) is irrelevant.

(E) is something we simply have to assume for science to have happened, but it doesn't explain the change.

Hope that helps!

-t

[rsarcone]

I was down to A and C as well, and went with A largely because of the word "easier". I figured just because they were easier to capture didn't mean that large birds weren't also captured.