Data from: Genome editing in butterflies reveals that spalt promotes and Distal-less represses eyespot colour patterns

Butterfly eyespot colour patterns are a key example of how a novel trait
can appear in association with the co-option of developmental patterning
genes. Little is known, however, about how, or even whether, co-opted
genes function in eyespot development. Here we use CRISPR/Cas9 genome
editing to determine the roles of two co-opted transcription factors that
are expressed during early eyespot determination. We found that deletions
in a single gene, spalt, are sufficient to reduce or completely delete
eyespot colour patterns, thus demonstrating a positive regulatory role for
this gene in eyespot determination. Conversely, and contrary to previous
predictions, deletions in Distal-less (Dll) result in an increase in the
size and number of eyespots, illustrating a repressive role for this gene
in eyespot development. Altogether our results show that the presence,
absence and shape of butterfly eyespots can be controlled by the activity
of two co-opted transcription factors.