Self-study
P1
The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent's fastest land animal, capable of running 90 kilometers per hour and of doing so for several kilometers. ███
Intro Topic ·
Pronghorn
Puzzling Phenomenon ·
Pronghorns' speed
Why are they faster than they need to be to escape any predator?
Biologist: Explanation ·
Speed was adapted for extinct predators
P2
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Others: SKEPTICAL ·
Others skeptical of relict behavior hypothesis
Relict behavior defined as behavior adapted to extinct conditions, e.g., extinct predators.
Others: Elaboration ·
Skeptical of hypothesis because difficult to test
Extinct conditions (e.g., predators) means no longer exist, so how can you test?
Support Biologist ·
Some evidence supporting general relict behavior hypothesis
But what about for pronghorns, specifically?
P3
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Support Biologist ·
Lots of evidence for pronghorn relict behavior hypothesis
Examples ·
Roam in herds, choose faster mates
Both behaviors once conferred evolutionary advantage but no longer do. Yet we still observe this relict behavior.
P4
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Support Biologist ·
Relict behavior in other animals
Examples ·
Stickleback, ground squirrels
Both exhibit relict behavior: they avoid extinct predators.
Elaboration ·
Relict behavior can disappear over time
Arctic squirrel lost extinct predator avoidance behavior after 3m years.
Passage Style
Phenomenon-hypothesis (RC)
Single position
16.
Which one of the following ████ ██████████ ██████ ███ ████ █████ ██ ███ ████████
a
Evidence from present-day ██████ ██████████ ████████ ████ ███ ██████ ███████ ████████ ███ ██████████ ████ ███ ███████████ ███████ ██ ███ ██████ ███ ████████ █████████ ██ ███ █████ ████████ █████████ ██ ██ ██████████ ██ █████████ ████ ████████
This best captures the author’s support for the hypothesis that the pronghorn’s speed is an adaptation to extinct predators. This hypothesis is expressed
b
Although some biologists ███████ ████ ███████ ██████ ████████████████ ████ ██ ███ █████ ██ ███ ██████████ ███ █████████ ██ █████████████ ██████████ ████ ████ ███ ███████ ███ ████ ██████ ██████ ████ ██████████ ██████ ██████ █████████ ████ ████ ██████████ █████████
The author doesn’t express doubt about the hypothesis that the pronghorn’s speed is an adaptation to extinct predators. The reference to arctic ground squirrels at the end of the passage is offered to show that relict behavior might not exist forever. It doesn’t show that relict behaviors don’t exist.
c
Research into animal █████████ ████████████ ████ ████ ██ ███ ██████████ ████████ ██████ ████████ ████ ████ ███████████ ███████████████ ██ ███████ ███ █████████ ██ █████████████ ██████████ ████ ████ ███ ███████ ███ ████ ██████
There’s no support for the claim that “most present-day characteristics” of animals are explained by environmental conditions that don’t exist anymore. Although the author does discuss some examples of relict behavior, she never suggests “most” present-day characteristics are relict behavior. Since (C) is not supported, it can’t be the main point.
d
Even in those █████ ██ █████ ██ ██████ ███████ ████████ ███████████████ ███████ █████████ ██ █████████████ █████████████ ███████████ ████████ ██████████ ██████ ██████ █████████ ████████ ████ █████ ███████████████ ████ ██████████ ██████████
Although the author might agree with (D), it is not the main point. The main point is that there’s support for the hypothesis that pronghorns’ speed is an adaptation to extinct predators. The reference to arctic ground squirrels at the end of the passage does suggest that relict behaviors won’t exist forever, but this is merely a side point that isn’t part of the author’s main argument.
e
Although biologists are ██████████ ██ ██████████ ████ ███ █████████ ██ █████ █████ ██ ███ ██████████ █████████ █████ ██████████ ████ ████ █████ ██ ██████ ███████████████ ███ ████ █████████ ██ ███████████ ██ ████████████ ██████████
The author doesn’t suggest that there is “widespread agreement among biologists” that many characteristics are adaptations to extinct predators. Also, (E) doesn’t capture the author’s opinion about what explains pronghorns’ speed. The passage is about a particular phenomenon (pronghorns’ speed) and a hypothesis for it. The main point isn’t about “many animal characteristics.”