Which vertebrate taxon or taxa originated as a result of duplication of Hox genes?

• A. Cephalochordates (lancelets)
• B. Echinoderms
• C. Urochordates (tunicates)
• D. Gnathostomes (jawed vertebrates)

Answer: (D)

Verified step by step guidance

1. Understand the role of Hox genes: Hox genes are a group of related genes that control the body plan of an embryo along the head-tail axis. Duplication of Hox genes allows for increased complexity in body structures and functions.
2. Review the evolutionary significance of Hox gene duplication: In vertebrates, the duplication of Hox genes is associated with the development of more complex anatomical features, such as jaws and paired appendages.
3. Identify the taxa in the question: Cephalochordates (lancelets) and Urochordates (tunicates) are invertebrate chordates, while echinoderms are non-chordate deuterostomes. Gnathostomes (jawed vertebrates) are a subgroup of vertebrates.
4. Connect Hox gene duplication to gnathostomes: The duplication of Hox genes is a key evolutionary event that occurred in the lineage leading to gnathostomes, enabling the development of jaws and other complex structures.
5. Conclude that gnathostomes (jawed vertebrates) are the taxon that originated as a result of Hox gene duplication, as this event is not associated with cephalochordates, echinoderms, or urochordates.