Final answer:
Hox genes have played a crucial role in the evolution of diverse animal body plans by regulating embryonic development as master control genes. They are responsible for the arrangement of body segments and appendages and have evolved through duplication, increasing complexity in body structures.
Step-by-step explanation:
Hox genes have been fundamental in shaping the diversity of animal body plans by acting as master control genes during development. These genes contain homeobox sequences and are responsible for determining the general body plan of an organism, including body segments, appendage placement, and head-tail directionality. Hox genes contribute to anatomical diversity by regulating embryonic development and determining body structure through the expression of transcription factors that activate or suppress a wide array of other genes.
The remarkable homology of Hox genes across different species also provides evidence for a common ancestor, as these genes are conserved throughout evolution. Mutations in Hox genes, such as those observed in the fruit fly, can have dramatic effects on body plan, including the misplacement of limbs. Moreover, the duplication of Hox genes over time allowed for increased complexity in animal body structures, contributing further to the diversity we see in today's animal kingdom.