It looks like the trend may be that many of the regulator genes appear from the earliest, e.g. like pre-programmed adaptation ability.
Are the Hox genes conserved across phyla like the eyeness gene, i.e. between human and mouse, 100% identical and between human and drosophilia, 94%? This is evidently the astonishing observation; IOW, it puts more emphasis on pre-programmed adaptation capability and less on random mutation branching away from the common ancestor(s).
It certainly looks like that. Also, I failed to give the link to the article I quoted University of Edinburgh .
Are the Hox genes conserved across phyla like the eyeness gene, i.e. between human and mouse,
Have not seen percentages, but many of the Hox genes in drosophyla are quite close to those in vertebrates. So much so that:
Functional similarity between Hox genes of different organisms demonstrated by gene swapping experiments: e.g. expression of human Hoxb4 in flies causes the same phenotype as overexpression of the fly homologue Deformed (Dfd).
From: University of Toronto.