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Difficulty: MediumLamarck's Theory of Evolution

A population of burrowing rodents living in permanent underground darkness possesses small, vestigial eyes covered by skin. According to Jean-Baptiste Lamarck's mechanism of evolution, which of the following best explains how these animals lost their functional eyesight?

  1. Continuous disuse of the eyes in darkness led to their gradual reduction during an individual's lifetime, and this acquired trait was inherited by offspring.Answer
  2. B
    Random genetic mutations resulting in smaller eyes conferred a survival advantage, leading to natural selection of blind individuals over time.
  3. C
    Perpetual darkness directly altered the DNA in the rodents' germ cells, causing immediate inherited loss of vision in subsequent generations.
  4. D
    The rodents intentionally chose to stop relying on their eyes, which immediately triggered genetic changes preventing eye development in offspring.

Answer

Continuous disuse of the eyes in darkness led to their gradual reduction during an individual's lifetime, and this acquired trait was inherited by offspring.
Lamarck's theory of evolution is built on two primary principles: the law of use and disuse (organs used extensively develop, while those unused atrophy) and the inheritance of acquired characteristics (somatic modifications gained during an organism's life are passed to offspring). The explanation stating that continuous disuse in darkness reduced the eyes and this acquired modification was inherited accurately reflects Lamarck's hypothesis.

Step-by-Step Solution

1
Identify the primary postulates of Lamarck's theory of evolution.
Lamarck's theory relies on two main ideas: the law of use and disuse, and the inheritance of acquired characteristics.
Understanding the core mechanism proposed by Lamarck is required to evaluate the scenario.
2
Apply the law of disuse to the scenario of subterranean rodents.
Living in complete darkness means the eyes are not used, causing them to degenerate or atrophy over the animal's lifetime.
Lamarck stated that organs not subjected to regular functional demand progressively shrink and lose function.
3
Apply the law of inheritance of acquired traits.
The reduced state of the eyes acquired during the parent's lifetime is transmitted to its offspring.
According to Lamarck, somatic changes developed through use or disuse are directly inheritable.

Key Concept

Lamarck's Law of Use and Disuse and Inheritance of Acquired Characteristics
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Topics

Lamarck's Theory of Evolution

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