Scientist: Support A small group of islands near Australia is inhabited by several species of iguana; Support closely related species also exist in the Americas, but nowhere else. βββ βββββββ ββ ββββββββ ββββββ ββββ βββββ βββ βββββββββββββ ββ βββββββββ βββ βββββββ ββββββββββββββ ββββ ββββββββ βββββββββββ βββββ βββββββ βββ ββββββββββ βββββ βββββ ββββββββββ βββββββββββ ββββ ββββ ββββββ ββ ββββββββ ββββββ ββββββ βββ βββββββ βββββ ββββ βββ βββββββββ
The scientist hypothesizes that the iguanasβ ancestors reached the islands near Australia by rafting from the Americas. As support, he points out that the only closely related species that currently exist are located in the Americas. He also notes that the islands first formed in isolation, away from any land masses, which implies that species could only exist there now if their ancestors had somehow arrived from elsewhere.
The scientist assumes that the closely related species in the Americas have the same ancestor as the island iguanas. He further assumes that this common ancestor has only ever lived in the Americas and nowhere else.
Which one of the following, ββ βββββ ββββ βββββββ βββ βββββββββββ βββββββββ
A number of ββββββ βββββββ ββββ βββββββ βββ βββββββ βββ βββ βββββ ββ βββ βββββββββ
The argument is only concerned with the origins of the iguana species. The potential origins of any other species are irrelevant.
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
Genetic analysis indicates ββββ βββ ββββββ βββββββ ββ βββ βββββββ βββ βββββββββ ββ βββββββ ββββββββ ββββ βββββ βββββ ββ βββ βββββββββ
The scientist doesnβt suggest or assume that the island iguanas are the same species as the American ones. His argument is that they merely share the same ancestor, and that this ancestor rafted from America to the islands. They may have evolved differently since that ancestor.
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
Documented cases of βββββββ βββββββ ββββ βββββββββ βββββββ ββββ ββββββ βββ βββββββββ
That documented cases are uncommon does not mean that this situation was impossible or even unlikely at the time.
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
Fossils of iguana βββββββ βββββββ βββββββ ββ βββββ ββββ βββββββ βββ βββββββ ββββ ββββ βββββ ββ ββββββββββ
This suggests that the island iguanasβ ancestor may have arrived from Australia, rather than from the Americas.
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
The lineages of ββββββββ βββββ βββ ββββββ βββββββ βββββ ββ βββββββββ ββ ββ βββββ βββββββ ββββ ββββ ββ β ββββββ βββββ ββ βββ βββββββββββββ ββ βββββββββ
The argument is only concerned with the origins of the islandβs iguana species. The potential origins of other species in other locations are irrelevant.
Weaken Qs: Answers that try to introduce an alternate explanation, but fall short, or try to explain a different phenomenon.
Strengthen Qs: Answers that try to eliminate an alternate explanation, but fall short, or try to eliminate an explanation for a different phenomenon.