Learning about genes, proteins, switches, 'genetic tool kits,' and the like has been particularly interesting. However, the part of this course that has been distinctively exciting is how these aspect of development are connected to evolution. As described in Endless Forms Most Beautiful by Sean B. Carroll, wing development sheds some light on powerful evidence of evolutionary development. From gills to wings, a few proteins have been identified as necessary components for this type of development. Specifically, Apterous and Nubbin have been found to be selectively expressed in areas where wing and gill development take place (i.e. the respiratory lobe in crustaceans).
It is evident that these homologous parts are significant in the study of evolutionary development. In fact, this particular case can tell us a lot about evolution of many species, including humans. Relating to Hox proteins and genetic switches, the repression or expression of specific products or parts, such as wings of insects, can be traced back. These genetic switches were involved in the development of signature sequences for Hox proteins that can result in either the 'turning on' or 'turning off' of particular segments. Therefore, differences in wing expression among separate species can be traced back to common Hox protein and the expression or repression of sequences and proteins.