Hox genes modify serial homology patterns in many organisms, exemplified in vertebrates by modification of the axial skeleton and in arthropods by diversification of the body segments. Butterfly wing eyespots also appear in a serial homologous pattern that, in certain species, is subject to local modification. A paper in EvoDevo reports the Hox gene Antp is the earliest known gene to have eyespot-specific expression; however, not all Lepidoptera express Antp in eyespots, suggesting some developmental flexibility.
Hombría, J. C. (2011, April 28). Butterfly eyespot serial homology: Enter the Hox genes. BMC Biology. https://doi.org/10.1186/1741-7007-9-26