Loggerhead turtles live and breed

Answer choices

1. A

   No Impact9% picked this

   Nesting sites of loggerhead turtles have been found off the Pacific coast of North America several thousand kilometers

   This is tempting at first as a possible Alternate Explanation, as in "oh, these juveniles in Baja didn't come from Japan; they came from up the pacific coast in North America!" But we weren't trying to explain "where did these juveniles in Baja come from". We were trying to explain "how come 95% of the DNA samples from the Baja turtles match the DNA from the Japanese turtles?" This answer doesn't provide an alternate explanation for that.

   9%
2. B

   Less Impact than Correct Answer9% picked this

   The distance between nesting sites and feeding sites of Atlantic loggerhead turtles is less

   This definitely weakens the plausibility of the author's storyline a little. She's trying to sell us on a story in which the nesting site and feeding site of Pacific loggerheads are 10,000 km apart. If Atlantic loggerheads travel less than 5,000 km from nesting side to feeding site, it makes it a little suspicious that Pacific loggerheads would be willing to go more than twice as far. But since they are distinct species, it's possible that Pacific loggerheads are adapted to travel farther distances. So this impugns the author's story a bit, but since it's talking about a different, though related, species it's not a super strong challenge.

   9%
3. C

   Unclear Impact12% picked this

   Loggerhead hatchlings in Japanese waters have been declining in number for the last decade while the number of nesting sites near the

   This answer is talking about "nesting sites" near Baja, which we never talked about before. We were discussing turtles feeding in Baja but having hatched in a nest in Japan. There might be zero nesting sites near Baja. So if that number has remained constant at zero, that won't really tell us anything. If this answer said "hatchlings in Japan have been declining in number for the last decade while the number of loggerheads feeding near Baja has remained constant", then that would hurt the plausibility of the author's storyline. Since she is selling us on this "born in Japan, feed in Baja" pipeline, she would expect that a dwindling of turtles born in Japan would eventually manifest in a dwindling of turtles feeding in Baja.

   12%
4. D

   Correct65% picked this

   Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from

   Why this is right

   This supplies an alternate explanation for the DNA match. It's not, as the author thinks, because these juvenile loggerheads in Baja were born in Japan. Instead, it's just because loggerhead DNA is pretty similar wherever you go. If 95% of the DNA from the Baja group matches DNA from a group of Atlantic loggerhead turtles, would we come to the conclusion that the Baja juveniles originally hatched in the Atlantic? No, because we were told that Pacific loggerheads and Atlantic loggerheads are distinct groups. They live and breed separately from each other. So this answer presents us with a case where there's a 95% DNA match, even though we know that the Baja juveniles did not hatch in the Atlantic. Thus, it makes the author's evidence feel worthless. She's saying, "These Baja juveniles must have hatched in Japan, since there's a 95% DNA match with loggerheads from Japan." And this answer allows us to say, "a 95% DNA match with a certain population is not good evidence that juveniles came from that population. After all, Pacific juveniles at Baja have a 95% DNA match with a population of Atlantic loggerheads, and we know the Pacific juveniles didn't come from that population."

   Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

   65%
5. E

   No Impact6% picked this

   Commercial aquariums have been successfully breeding Atlantic loggerheads with Pacific loggerheads for the

   The loggerheads we're analyzing are not cross-breeds and they don't live in an aquarium, so it doesn't seem like this answer has any relevance to the conversation at hand.

   6%