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Difficulty: EasyEvolution and Adaptation

A population of Arctic foxes lives in a snowy tundra habitat where white coat coloration provides effective camouflage against both predators and prey. According to the theory of natural selection, which of the following best explains how white fur became predominant in this population over generations?

  1. A
    Individual foxes intentionally altered their pigment production to turn white in response to living on snow.
  2. Foxes with inherited genetic variations for white fur survived and reproduced more successfully in snowy surroundings.Answer
  3. C
    White fur alleles automatically became frequent because dominant genetic traits always replace recessive traits over time.
  4. D
    Foxes developed white fur from physical exposure to freezing temperatures and passed those newly acquired coats directly to their offspring.

Answer

Foxes with inherited genetic variations for white fur survived and reproduced more successfully in snowy surroundings.
Natural selection operates on pre-existing heritable genetic variations within a population. In a snowy environment, foxes with lighter or white fur are better camouflaged, allowing them to evade hazards and capture prey more effectively. Because these individuals survive longer and reproduce more successfully, they pass their white fur alleles to their offspring, increasing the trait's prevalence over generations.

Step-by-Step Solution

1
Identify the environmental pressure and the adaptive trait.
The snowy tundra environment favors camouflage, making white fur advantageous for survival and hunting.
Natural selection requires an environmental selective pressure acting on a specific phenotypic trait.
2
Apply the core mechanism of natural selection.
Foxes born with heritable variations for lighter or white coats had higher survival and reproductive rates (differential reproductive success).
Evolution by natural selection relies on heritable variation and differential reproduction, not individual adaptation during a lifetime.
3
Determine the generational outcome for the population.
Over many generations, the frequency of alleles responsible for white fur increased in the population.
Populations evolve over generations as beneficial alleles are passed to offspring more frequently.

Key Concept

Natural Selection and Differential Reproductive Success
Estimated Time:45s
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Topics

Evolution and Adaptation

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