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Difficulty: MediumDarwin's Theory of Natural Selection

In a population of moths inhabiting an industrial region, dark-colored individuals became significantly more common over several generations as pollution darkened the tree trunks. According to Charles Darwin's theory of natural selection, which mechanism best accounts for this change in the population?

  1. Pre-existing dark genetic variations provided a camouflage advantage against predators, resulting in higher survival and reproduction rates for dark moths.Answer
  2. B
    Individual light-colored moths actively developed darker wing pigments during their lifetime to adapt to the soot and passed these acquired traits to their offspring.
  3. C
    Environmental soot directly induced beneficial genetic mutations in all light moths to prevent the species from going extinct.
  4. D
    Light-colored moths stopped using their light wing pigments, causing the light coloration to deteriorate and disappear over generations.

Answer

Pre-existing dark genetic variations provided a camouflage advantage against predators, resulting in higher survival and reproduction rates for dark moths.
According to Darwin's theory of natural selection, populations contain natural genetic variations. When the environment changed due to industrial pollution, dark moths gained a camouflage advantage. They were preyed upon less frequently by birds, allowing them to survive and pass their dark-pigment genes to the next generation at higher rates.

Step-by-Step Solution

1
Identify the foundation of Darwinian evolution.
Natural selection requires inherited genetic variation to already exist within a population prior to environmental change.
Organisms do not generate intentional phenotypic changes within their lifetime to suit new environments.
2
Analyze the environmental selective pressure.
Soot-covered trees made dark moths less visible to predators compared to light-colored moths.
Selective pressures determine which existing phenotypes offer a survival advantage.
3
Determine the population-level outcome.
Darker moths survived longer and produced more offspring, increasing the proportion of dark moths in future generations.
Differential survival and reproduction cause advantageous alleles to accumulate in the population over time.

Key Concept

Natural Selection and Differential Reproduction
Estimated Time:1m 0s
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Topics

Darwin's Theory of Natural Selection

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