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Difficulty: EasyEvidence for Evolution: Comparative Anatomy, Embryology, and Vestigial Organs

The forelimb of a horse and the flipper of a whale share a similar internal skeletal framework despite performing completely different functions in their respective environments. Which of the following correctly classifies these structures and identifies their evolutionary significance?

  1. Homologous structures resulting from divergent evolutionAnswer
  2. B
    Analogous structures resulting from convergent evolution
  3. C
    Analogous structures resulting from divergent evolution
  4. D
    Homologous structures resulting from convergent evolution

Answer

Homologous structures resulting from divergent evolution
The forelimb of a horse and the flipper of a whale are homologous structures because they share a fundamental pentadactyl bone organization derived from a common vertebrate ancestor. Natural selection modified this common structure for different functional demands (running versus swimming), demonstrating divergent evolution.

Step-by-Step Solution

1
Examine the origin and internal skeletal structure of the horse forelimb and whale flipper.
Both organs exhibit the pentadactyl limb pattern derived from a common vertebrate ancestor.
Organs that share a common anatomical framework and embryological origin are defined as homologous structures.
2
Determine the type of evolutionary process responsible for these modifications.
Adaptations to terrestrial locomotion and aquatic swimming caused the shared ancestral limb to diverge into different forms.
Divergent evolution occurs when related species adapt a shared ancestral feature for different ecological functions.

Key Concept

Homologous structures and divergent evolution in comparative anatomy
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Topics

Evidence for Evolution: Comparative Anatomy, Embryology, and Vestigial Organs

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