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
21.
The third paragraph of the ███████ ████████ ███ ████ ███████ ███ █████ ███ ██ ███ █████████ ███████████
a
Predators do not ██████ ███████ ███████ ████ ███ █████████ ████ ██████
Too strong. Although the author does mention that herds can help a pronghorn “watch for predators” and “diminish the chances of any particular animal being attacked,” this doesn’t support the claim that predators “do not attack” grazing animals in herds. They may still attack herds — it’s just that on average, an individual member of the herd decreases its chances of being among the animals that are caught and eaten.
b
Pronghorns tend to █████ ██ █████ ████ ████ ████ █████ █ ██████ ████ █████████ █████ ███
Not supported, because the author never suggests there are any conditions or requirements on when the pronghorns will graze in herds. Although we only get mention of benefits related to predators, this doesn’t imply that pronghorns only herd when predators are nearby. Perhaps pronghorns generally herd, regardless of whether predators are nearby, so that they can benefit if a predator comes along.
c
If animals do ███ █████ ███ █████ █████ ████ ██ ███ ████ ██ ██████
Not supported, because although we know that many grazing animals herd, this doesn’t imply that only grazing animals herd. Maybe non-grazing animals herd and also get benefits from herding.
d
Female pronghorns mate ████ ████ ███ ███████ ████ █████████ ██ ███ █████
Too strong. Although the author does indicate that female pronghorns “choose mates based on [speed and endurance],” this doesn’t imply that they mate “only” with the fastest male pronghorn. Maybe the top few pronghorns mate with females, or the top 10%. Also, speed is only one aspect of the athletic abilities mentioned.
e
If pronghorns did ███ █████ ████ █████ ███ ████ █████████████ ███████ ██████ ████ ███████████ ███████████