While the most abundant and dominant species within a particular ecosy

KarishmaB GMATNinja

For Q1, why E is incorrect?
(E) The fact that there is great species diversity within some habitats occupied by P. ochraceus
Author has mentioned in the last sentence that species diversity could impact the keystone species status. Why E is incorrect then. I agree that community diversity could affect when a reduction in species diversity occur but in broader terms, diversity in general could affect.

In Q4, why C is incorrect?
(C) Such an identification is likely to be less reliable as an ecosystem becomes less diverse.
Acc to last line, identification depends on a diverse environment. So a less diverse environment could affect keystone status. Why can't we infer C from this sentence.

Thank you for your time

Question 1

Question 1 asks us which answer is specifically mentioned in the passage regarding P. ochraceus.

In that last sentence, the author isn't talking specifically about P. ochraceus any more. Instead, he/she is talking generally about what might keystone status for any species.

So, could great species diversity within some habitats occupied by P. ochraceus impact its keystone status? Sure! But the author doesn't mention that species diversity ACTUALLY impacts P. ochraceus's status. By contrast, the author DOES specifically mention that P. ochraceus's role is impacted by the degree to which its habitat is sheltered from waves.

(E) is out and (A) is the correct answer for question 1.

Question 4

Here's the exact language of question 4:

(C) then says that "such an identification is likely to be less reliable as an ecosystem becomes less diverse."

Hmm. (C) isn't directly talking about how to tell whether something is a keystone species (and your'e absolutely right that a less diverse environment could affect keystone status). This is talking about how reliable the identification is. In other words, how sure are you that a certain species is or is not a keystone?

There's nothing in the passage implying that this identification is more or less reliable in one situation or another. You could be very confident about whether something is a keystone in a very diverse environment, and equally confident about whether its a keystone in a non-diverse environment.

We can eliminate (C) for question 4 because there's nothing implying that one situation makes identifying keystone species less reliable than another.

I hope that helps!

4/4 in 5 minutes. I find myself more comfortable with sciences topics than with humanities topics