Answer
Though millions of years have passed since the numerous animal phylums have had a common ancestor, the Hox genes have been conserved and are found in every single animal species. Two groups of Hox genes are in cnidarians. The number of Hox genes increases as complexity of the animal increases. Vertebrates have the most Hox genes, which appear not only in higher numbers per cluster but appear in four clusters, each on a different chromosome.
Work Step by Step
Though millions of years have passed since the numerous animal phylums have had a common ancestor, the Hox genes have been conserved and are found in every single animal species. Two groups of Hox genes are in cnidarians. The number of Hox genes increases as complexity of the animal increases. Vertebrates have the most Hox genes, which appear not only in higher numbers per cluster but appear in four clusters, each on a different chromosome.
