Editing Butterfly (section)

==== Pattern formation ====

The colourful patterns on many butterfly wings tell potential predators that they are toxic. Hence, the genetic basis of wing [[pattern formation]] can illuminate both the [[evolution]] of butterflies as well as their [[developmental biology]]. The colour of butterfly wings is derived from tiny structures called scales, each of which have their own [[pigment]]s. In ''[[Heliconius]]'' butterflies, there are three types of scales: yellow/white, black, and red/orange/brown scales. Some mechanism of wing pattern formation are now being solved using genetic techniques. For instance, a [[gene]] called ''cortex'' determines the colour of scales: deleting ''cortex'' turned black and red scales yellow. Mutations, e.g. [[Transposable element|transposon insertions]] of the [[non-coding DNA]] around the ''cortex'' gene can turn a black-winged butterfly into a butterfly with a yellow wing band.<ref>{{Cite journal |last1=Livraghi |first1=Luca |last2=Hanly |first2=Joseph J |last3=Van Bellghem |first3=Steven M |last4=Montejo-Kovacevich |first4=Gabriela |last5=van der Heijden |first5=Eva SM |last6=Loh |first6=Ling Sheng |last7=Ren |first7=Anna |last8=Warren |first8=Ian A |last9=Lewis |first9=James J |last10=Concha |first10=Carolina |last11=Hebberecht |first11=Laura |date=2021-07-19 |title=Cortex cis-regulatory switches establish scale colour identity and pattern diversity in Heliconius |journal=eLife |volume=10 |pages=e68549 |doi=10.7554/eLife.68549 |pmid=34280087 |issn=2050-084X |pmc=8289415 |doi-access=free }}</ref>