[Campbell Biology P.515] The treehopper insect possesses an ornate helmet resembling wings o... | Practice Question

The treehopper insect possesses an ornate helmet resembling wings on its first thoracic segment, despite modern insects typically only having wings on their second and third segments due to Hox gene products inhibiting wing formation on the first segment. How could changes in gene regulation explain the evolution of this unique structure?

  • A: A mutation caused a novel gene to emerge that directly codes for the helmet structure.
  • B: Changes in regulatory DNA led to the de-repression or altered expression patterns of Hox genes in the first thoracic segment, allowing wing-like growth.
  • C: The treehopper acquired a new set of Hox genes through horizontal gene transfer, introducing the helmet-forming ability.
  • D: The helmet evolved due to a higher rate of random point mutations in structural genes of the first thoracic segment.

Explanation

The text states that in modern insects, Hox gene products inhibit wing formation on the first segment. The treehopper's helmet on the first segment suggests a change that bypassed this inhibition. This is best explained by changes in regulatory DNA affecting the expression pattern of Hox genes, leading to the de-repression of wing-forming pathways or the redirection of developmental resources to form the helmet structure in an atypical location.