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Zorluk: OrtaEvolution and Adaptation

Modern baleen whales possess reduced, nonfunctional pelvic and hind limb bones embedded within their abdominal wall. Which statement best explains the evolutionary significance of these structures?

  1. A
    They formed because individual ancestral whales actively shed their external hind limbs during their lifetimes to swim faster.
  2. They are vestigial structures inherited from four-legged terrestrial ancestors.Cevap
  3. C
    They represent dominant genetic traits that will automatically become more frequent and larger in all marine mammals.
  4. D
    They are acquired anatomical adaptations developed by individual whales practicing diving maneuvers.

Cevap

The reduced pelvic bones in modern whales are vestigial structures inherited from four-legged terrestrial ancestors.
The correct answer identifies these pelvic bones as vestigial structures. Vestigial structures are remnants of organs or skeletal elements that were fully functional in ancestral species. The presence of internal pelvic and hind limb remnants in whales provides anatomical evidence that cetaceans evolved from four-legged terrestrial ancestors through gradual evolutionary changes.

Adım Adım Çözüm

1
Identify the anatomical nature of the nonfunctional limb bones in whales.
The structures are anatomical remnants that have lost their original ancestral function.
Anatomical features that serve little or no current purpose but are homologous to functional structures in related species or ancestors are classified as vestigial structures.
2
Determine the evolutionary significance of these vestigial remnants.
They provide physical evidence that whales share common ancestry with four-legged terrestrial mammals.
Over millions of years, natural selection favored reduced hind limbs as ancestral cetaceans adapted to a fully aquatic environment, leaving reduced pelvic bones behind.

Anahtar Kavram

Vestigial structures provide anatomical evidence of common descent and evolutionary change over generations.
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Evolution and Adaptation

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