#15 - Loggerhead turtles live and breed in distinct groups

[sdb606]

I've gotten this wrong twice now. I still don't see how D is correct. I didn't really like any of the choices.

If I were the author and someone challenged me with D, I would say, "The Baja turtles could be mating at BOTH the Japan site and the Atlantic. Just because the turtles resemble the Atlantic kind doesn't mean they can't also resemble the Japanese kind.

I liked C because I think it's very reasonable to assume a rough correlation between number of turtles and number of nesting sites. If a site has 1 million turtles, I expect to find more nesting sites than if it had 1 turtle. Although the reason I didn't like C was because of the possibility that the Baja turtles could have multiple hatching sites elsewhere that are growing and compensating for the decrease in Japan.

Dave Killoran, elsewhere on the forum, posted about not being clinically logical on Weaken questions and allow some wiggle room. I think that's what I'm doing here.

I could see how D could be the clear answer if the stimulus had said it is impossible for Baja turtles to reach the Atlantic but it doesn't say that. Assuming you know Baja is near Central America, why can't the turtles swim around Argentina and hatch in the South Atlantic in addition to Japan? That would explain the genetic similarities and not weaken the argument.

[QueensULawHopefully]

How do you know which part of the stimulus is the conclusion

[Robert Carroll]

Samuel,

The stimulus sets up that a 95% match in DNA indicates a commonality of origin. Answer choice (D) shows that, if we consider 95% DNA match to indicate that, we now have the same level of matching in another population, so either the 95% matching wasn't a good standard, or else there's just as much evidence of an Atlantic origin, weakening the argument either way.

For answer choice (C), there is no indication in the stimulus that there even are any Baja nesting sites. Some turtles feed near the Baja peninsula, but there may be 0 nesting sites there. So saying there are fewer nesting sites there isn't going to weaken the argument, but be perfectly consistent with it.


QueensU,

"New evidence suggests" means "this evidence helps show the following", so whatever the evidence supposedly suggests would be the conclusion.

Robert Carroll

[Rawan Barakat]

I am having great difficulty trying to understand why answer choice (C) is incorrect and what it is trying to say. Any help clearing that up will be greatly appreciated. Thank you!

[Adam Tyson]

Happy to help, Rawan Barakat! Answer C is about nesting sites near the Baja peninsula, but the argument isn't about turtles that nest there. It's about the ones that feed there! If they hatched on the other side of the Pacific, somewhere near Japan, they probably came from nests near Japan and having nothing to do with the nesting sites around Baja!

To add to the problem, the number of nesting sites may have nothing to do with the number of turtles that hatch. Maybe just as many turtle mothers are making nests and laying eggs, but not as many of the eggs are hatching. Maybe disease, or climate change, or predators, etc. are reducing the number of turtles that hatch and survive, even though there are as many nests as there ever were.

The main problem, though, is that first one - the number of nests near Baja is irrelevant. This answer would be more useful if it told us something about the number of turtles that feed near Baja and compared that number to the number that hatch near Japan.

[jupiterlaw]

Samuel,

The stimulus sets up that a 95% match in DNA indicates a commonality of origin. Answer choice (D) shows that, if we consider 95% DNA match to indicate that, we now have the same level of matching in another population, so either the 95% matching wasn't a good standard, or else there's just as much evidence of an Atlantic origin, weakening the argument either way.

For answer choice (C), there is no indication in the stimulus that there even are any Baja nesting sites. Some turtles feed near the Baja peninsula, but there may be 0 nesting sites there. So saying there are fewer nesting sites there isn't going to weaken the argument, but be perfectly consistent with it.


QueensU,

"New evidence suggests" means "this evidence helps show the following", so whatever the evidence supposedly suggests would be the conclusion.

Robert Carroll

Hi,

1. I am confused on how the stimulus "sets up that a 95% match in DNA indicates a commonality of origin", I am not really seeing this connection.

2. Also, there's a disconnect in my mind about what exactly the author is trying to say by following up the conclusion (juvenile pacific loggerheads that feed near Baja hatch in Japan 10,000 km away) with saying that 95% if DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites. I am not understanding what the author is getting at. Additionally, when are the "Baja turtles" referencing juvenile pacific loggerheads feeding near Baja?

3. I am still having trouble understanding how D weakens the argument. I understand how all other answer choices to not weaken, but I don't see what D is attacking. The conclusion is that juvenile pacific loggerheads that feed near Baja hatch in Japan, 10,000 km away, and I don't see how D weakens this. In my mind, stating that 95% of the DNA samples taken from Baja turtles matches those taken from Atlantic loggerhead turtles doesn't weaken that 95% of their DNA can also match that of Pacific loggerheads.

Thanks!

[jupiterlaw]

Samuel,

The stimulus sets up that a 95% match in DNA indicates a commonality of origin. Answer choice (D) shows that, if we consider 95% DNA match to indicate that, we now have the same level of matching in another population, so either the 95% matching wasn't a good standard, or else there's just as much evidence of an Atlantic origin, weakening the argument either way.

For answer choice (C), there is no indication in the stimulus that there even are any Baja nesting sites. Some turtles feed near the Baja peninsula, but there may be 0 nesting sites there. So saying there are fewer nesting sites there isn't going to weaken the argument, but be perfectly consistent with it.


QueensU,

"New evidence suggests" means "this evidence helps show the following", so whatever the evidence supposedly suggests would be the conclusion.

Robert Carroll

Hi,

1. I am confused on how the stimulus "sets up that a 95% match in DNA indicates a commonality of origin", I am not really seeing this connection.

2. Also, there's a disconnect in my mind about what exactly the author is trying to say by following up the conclusion (juvenile pacific loggerheads that feed near Baja hatch in Japan 10,000 km away) with saying that 95% of DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites. I am not understanding what the author is getting at. Additionally, are the "Baja turtles" referencing the juvenile pacific loggerheads that feed near Baja?

3. I am still having trouble understanding how D weakens the argument. I understand how all other answer choices do not weaken, but I don't see how D effectively attacks the argument. The conclusion is that juvenile pacific loggerheads that feed near Baja hatch in Japan, 10,000 km away, and I don't see how D weakens this. In my mind, stating that 95% of the DNA samples taken from Baja turtles matches those taken from Atlantic loggerhead turtles doesn't weaken that 95% of their DNA can also match that of Pacific loggerheads.

Thanks!

corrections are bolded!

[Luke Haqq]

Hi jupiterlaw!

The conclusion to this stimulus is the second sentence, "New evidence suggests that juvenile Pacific loggerheads that feed near the Baja peninsula hatch in Japanese waters 10,000 kilometers away." This mentioned evidence was that 95% of the DNA samples taken from the Baja turtles (we don't know exactly how these relate to the other mentioned turtles) match those taken from the juvenile Pacific loggerheads at their nesting sites.

That evidence might seem to support the conclusion. However, if 95% of the DNA samples match Atlantic loggerhead turtles too, as (D) supposes, and 95% match Pacific loggerheads, then the mentioned evidence isn't enough to reach the conclusion. The Baja turtles seem as genetically similar to Atlantic loggerheads as they do to Pacific loggerheads.

[pineapplelover18]

okayyyy so I attempted this question and got to the right AC fairly quickly doing this:

the stim says there's some loggerheads in the pacific and some in Atlantic. It claims that juvenile turtles from the pacific feed NEAR the Baja, therefore they must be the ones hatching in the Japanese waters, bc 95% of the turtles sampled on were from the BAJA waters. What jumped out immediately was the the author mentions 2 places the turtles could have come from (Atlantic or Pacific) and then assumes it is the pacific turtles who are the ones who hatch. What if the Atlantic turtles also somehow feed near and take a trip from or to the Japanese waters? the author can not assume 1 possibility here.

Also, they said DNA matches, what if the DNA matches bc they are TURTLES? Obviously there is going to be overlap among DNA.

[Rachael Wilkenfeld]

Great Pineapple! Exactly right---we don't know how much DNA typical turtles share with other turtles. If it's true that the ones we know are from a different area (Atlantic) share 95%, we'd have no reason to think that the ones in Baja that share DNA with the ones from Japan are in any way related.

Keep up the good work