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Difficulty: HardNecessary Assumption

Wildlife Biologist: Recent tests reveal that urban coyotes exhibit baseline cortisol levels—a primary indicator of physiological stress—that are significantly higher than those of rural coyotes. Yet over the past decade, the number of pups born annually in the urban coyote population has increased dramatically. Clearly, elevated cortisol levels do not impede reproductive success in coyotes.

The wildlife biologist's argument relies on which of the following assumptions? (Select all that apply.)

  1. The elevated cortisol levels observed in the urban population are not confined exclusively to non-breeding coyotes.Answer
  2. The high baseline cortisol levels in urban coyotes are present during the specific times of year when the animals are mating and gestating.Answer
  3. C
    Any coyote population living in an urban environment will experience a dramatic increase in its annual birth rate regardless of its physiological stress levels.
  4. D
    Urban coyotes have access to abundant anthropogenic food sources that completely offset the metabolic toll of severe physiological stress.
  5. E
    Elevated baseline cortisol levels are the primary cause of the dramatic increase in the number of pups born to the urban coyote population.

Answer

The argument depends on two assumptions: that the elevated cortisol is not isolated only in the non-breeding coyotes, and that the cortisol is actually present during the mating and gestating periods.
For the author to conclude that high cortisol does not impede reproduction based on the urban coyote population's birth rate, the author MUST assume that the high cortisol is actually interacting with the reproductive process. This requires two 'defender' assumptions: the stress cannot be isolated demographically (only in non-breeders) and it cannot be isolated temporally (only present outside of mating season). If either of these boundaries existed, the argument's evidence would be irrelevant to its conclusion.

Step-by-Step Solution

1
Identify the core components of the argument.
Premise: Urban coyotes have high cortisol and produce many pups. Conclusion: High cortisol does not impede reproductive success.
Deconstructing the stimulus is required to isolate the logical gap between the evidence provided and the absolute claim made in the conclusion.
2
Analyze the logical gap in the reasoning.
The author assumes that the physiological state (high cortisol) is actually interacting with the biological process (reproduction).
If a trait is observed in a population, it cannot be assumed to affect a specific mechanism unless it is present in the individuals performing that mechanism, at the time they are performing it.
3
Evaluate the choices using the Negation Test.
Negating the correct options severs the connection between the high cortisol and the act of reproducing, which destroys the author's ability to draw a conclusion about their relationship.
The Negation Test is the most definitive way to verify if an assumption is strictly logically necessary.

Key Concept

Necessary Assumption (Defender Strategy)
Estimated Time:2m 0s
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Topics

Necessary Assumption

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