Many Seychelles warblers of breeding age forgo breeding, remaining instead with their parents and helping to raise their own siblings. This behavior, called cooperative breeding, results from the scarcity of nesting territory for the birds on the tiny island that, until recently, was home to the world’s population of Seychelles warblers. Yet when healthy warblers were transplanted to a much larger neighboring island as part of an experiment, most of those warblers maintained a pattern of cooperative breeding.

"Surprising" Phenomenon
Why did most of the healthy warblers transplanted to the neighboring island maintain a pattern of cooperative breeding when the neighboring island was much larger than Seychelles?

Objective
The correct answer must address something about the nature of the transplanted warblers or environmental factors affecting the warblers that help explain why most of the warblers maintained a pattern of cooperative breeding.

A
Many of the Seychelles warblers that were transplanted to the neighboring island had not yet reached breeding age.
Regardless of how many of the warblers had reached breeding age, we know the majority of the healthy warblers transplanted to the island maintained a pattern of cooperative breeding. (A) doesn’t help explain this phenomenon.
B
The climate of the island to which Seychelles warblers were transplanted was the same as that of the warblers’ native island.
We don’t know if climate affects warblers’ breeding habits. (B) gives us information that doesn’t aid our understanding of the phenomenon in the stimulus.
C
Most of the terrain on the neighboring island was not of the type in which Seychelles warblers generally build their nests.
This identifies an environmental factor on the neighboring island that could affect warbler breeding habits. If most of the terrain on the new island was not of the type warblers typically use for their nests, it may have caused many to maintain a pattern of cooperative breeding.
D
Cooperative breeding in species other than the Seychelles warbler often results when the environment cannot sustain a rise in the population.
We don’t know if the cooperative breeding habits of other species are indicative of the breeding habits of Seychelles warblers. (D) is irrelevant.
E
The Seychelles warblers had fewer competitors for nesting territory on the island to which they were transplanted than on their native island.
This may compound the phenomenon, as less competition for nesting could provide warblers with more space to raise offspring. The transplanted warblers having fewer nesting competitors isn’t an explanation for why many of those warblers maintained a cooperative breeding pattern.

7 comments

While 65 percent of the eligible voters who were recently polled favor Perkins over Samuels in the coming election, the results of that poll are dubious because it was not based on a representative sample. Given that Perkins predominantly advocates the interests of the upper-middle class and that the survey was conducted at high-priced shopping malls, it is quite probable that Perkins’s supporters were overrepresented.

Summarize Argument: Counter-Position
The author concludes that the results of a recent election poll are questionable. The support for this comes from the idea that the poll was conducted in high-priced shopping malls. Because Perkins’s policies support the upper-middle class, it is likely that her supporters are overrepresented at the expensive malls. This means that the sample for the poll was biased, so the results of the poll are probably not representative of the views of eligible voters in general.

Identify Conclusion
The conclusion is that the results of the election poll may not be accurate: “the results of that poll are dubious.”

A
The poll was intentionally designed to favor Perkins over Samuels.
There is no indication in the argument that the problematic design of the poll was intentional, so this is not the conclusion.
B
Samuels’s supporters believe that they were probably not adequately represented in the poll.
There is no discussion of what the supporters of Samuels believe, so this is not the main conclusion.
C
The poll’s results probably do not accurately represent the opinions of the voters in the coming election.
This is the main conclusion. This is a paraphrase of the part of the argument that was identified as the conclusion. Further, the rest of the argument acts as support for this claim.
D
Samuels is quite likely to have a good chance of winning the coming election.
The argument does not give any indication of the accurate polling numbers; we just know that the poll discussed in the argument might not be accurate. This is unsupported from the argument, so it is not the main conclusion.
E
Those who designed the poll should have considered more carefully where to conduct the survey.
This kind of value judgement (what poll designers “should have considered”) is not included in the argument, so this is not the main conclusion.

4 comments

Since 1989 the importation of ivory from African elephants into the United States and Canada has been illegal, but the importation of ivory from the excavated tusks of ancient mammoths remains legal in both countries. Following the ban, there was a sharp increase in the importation of ivory that importers identified as mammoth ivory. In 1989 customs officials lacked a technique for distinguishing elephant ivory from that of mammoths. Just after such a technique was invented and its use by customs officials became widely known, there was a dramatic decrease in the amount of ivory presented for importation into the U.S. and Canada that was identified by importers as mammoth ivory.

Summary
Since 1989, importing ivory from African elephants into the US and Canada has been illegal. But, importing ivory from ancient mammoths is legal. Following the 1989 ban on importing elephant ivory, there was a sharp uptick in ivory imports labeled as mammoth ivory. However, once a technique was developed to reliably distinguish between elephant and mammoth ivory, there was a dramatic decline in the amount of imported ivory labeled as mammoth ivory.

Strongly Supported Conclusions
Before the technique to distinguish between the two types of ivory was introduced, much of the ivory labeled mammoth ivory was actually elephant ivory.

A
Customs officials still cannot reliably distinguish elephant ivory from mammoth ivory.
This is antisupported. The stimulus says that a technique was discovered and widely known.
B
Most of the ivory currently imported into the U.S. and Canada comes from neither African elephants nor mammoths.
The stimulus does not provide information about the current sources of most ivory imports.
C
In the period since the technique for distinguishing elephant ivory from mammoth ivory was implemented, the population of African elephants has declined.
The stimulus does not give any information about the population of elephants. You need a few assumptions to make this work.
D
Much of the ivory imported as mammoth ivory just after the ban on ivory from African elephants went into effect was actually elephant ivory.
The stimulus explains that following the ban, there was a significant increase in mammoth ivory imports and a massive decrease once a technique to distinguish between the two ivories was implemented. You can assume that many ivory imports were mislabeled to get around the law.
E
Shortly after the importation of ivory from African elephants was outlawed, there was a sharp increase in the total amount of all ivory presented for importation into the U.S. and Canada.
The stimulus says that there was a massive increase in mammoth-labeled ivory, not an overall increase in the *total* amount of ivory imported.

12 comments