Fig. 1
From: Conservation and flexibility in the gene regulatory landscape of heliconiine butterfly wings
Hypothetical mechanisms of wing pattern development and evolution. In this model, a set of prepatterning factors (a) are expressed early in the developing wing, may pattern the development of the wing and do not vary in their expression profiles in different morphs or species (see Table 1). These factors feed in to the regulation of the wing pattern switch genes and shape their expression profiles accordingly, for example in Heliconius the transcription factor optix (b), which causes scale cells that would otherwise develop to be melanic to express ommochrome pigments (c). It is also possible that changes to the expression of wing pattern switch genes like optix could be caused by changes in expression of prepatterning factors (d)