felixduan320 wrote:
Thanks for sharing this. A few things. Wouldn't the term "generalist", which suggests that they can pollinate more than one flower, indicate that a generalist would pollinate according to preference, and not abundance? It would make more sense for a specialist to prioritize abundance, since they can only feed on a select few flowers, whereas a generalist has more choices and can therefore be more picky. This would make Answer C more correct.
In addition, Answer A specifically mentions "at times significantly lower", whereas the excerpt in the passage quotes "their abundance may be CHRONICALLY low relative to the availability of flowers". It seems to be the passage is suggesting the only chronically low abundance would be a reliability issue, but if it happens once in a while ("at times"), the effects are not significant enough to warrant the "unreliable" label.
Let me know if the above makes sense. Based on the logic above, I am still struggling to understand why B is correct and not C. Thank you!
The passage tells us that a generalist can be an unreliable pollinator because its "fidelity to a particular species depends on the
availability of alternative food sources."
This tells us that a generalist doesn't really have a preference for which plant it eats -- it just eats whatever is most readily available. Let's say that out of plants X, Y, and Z, only plant X is available. Generalists will just eat plant X and be happy to do so! Now say that plants Y and Z move into the area -- the generalist doesn't remain faithful to plant X, but eats whatever is most convenient. Plant X will not get as much attention from the generalist -- so from plant X's perspective, the generalist is an
unreliable pollinator when other plants are available for it to feed on.
The main point is that the generalist doesn't choose what it eats based on preference -- it chooses based on availability.
Take another look at (C):
Quote:
C. A dietary generalist for whom that flower’s nectar is not a preferred food but is the most consistently available food [is an unreliable pollinator].
Based on the discussion above, we know that generalists decide what to eat based on availability. So, it will reliably eat (and therefore pollinate) "the most consistently available food." This is essentially the opposite of answer choice (C), so (C) is incorrect.
To understand why (B) is correct, take a look at the two reasons identified in the passage to explain why a specialist may be an unreliable pollinator:
- "their abundance may vary widely from year to year, resulting in variable pollination of their preferred food species." OR
- " their abundance may be chronically low relative to the availability of flowers."
Now take a look at answer choice (B):
Quote:
B. A dietary specialist whose abundance is at times significantly lower than that of the flower
You are correct to point out that (B) doesn't align well with a case in which the specialist population is "chronically low." However, this answer choice does fit nicely with the other case, in which the specialists' "abundance may vary widely." Because (B) specifically tells us that the specialist's abundance is "at times significantly lower than that of the flower," we can say that it is not consistently available to pollinate all of the flowers. Therefore, this particular specialist is an unreliable pollinator, and (B) is correct.
I hope that helps!
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10 Oct 2021, 08:43
