[Campbell Biology P.513] The text states that 'small changes in regulatory sequences of part... | Practice Question

The text states that 'small changes in regulatory sequences of particular genes cause changes in gene expression patterns that can lead to major changes in body form.' Which of the following examples from the text best exemplifies this principle in the context of evolutionary diversification?

  • A: The conservation of the homeodomain sequence across diverse animal species, ensuring identical body plans.
  • B: The presence of identical Hox genes in both segmented insects and nonsegmented sea urchins, yet resulting in vastly different body structures.
  • C: The role of homeobox genes in coordinating the transcription of developmental gene batteries, leading to complex organ formation.
  • D: The ability of homeodomain-containing proteins to recognize specific enhancers, which remain unchanged during evolution.

Explanation

The text explicitly mentions that sea urchins, despite having Hox genes, have a nonsegmented body plan quite different from insects and mice. This highlights how similar underlying genes, through changes in their regulatory control and expression patterns implied by 'small changes in regulatory sequences' , can lead to significant morphological divergence.