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Cortex cis-regulatory switches establish scale colour identity and pattern diversity in Heliconius.

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Van Bellghem, Steven M  ORCID logo
Montejo-Kovacevich, Gabriela  ORCID logo
van der Heijden, Eva Sm 


In Heliconius butterflies, wing colour pattern diversity and scale types are controlled by a few genes of large effect that regulate colour pattern switches between morphs and species across a large mimetic radiation. One of these genes, cortex, has been repeatedly associated with colour pattern evolution in butterflies. Here we carried out CRISPR knockouts in multiple Heliconius species and show that cortex is a major determinant of scale cell identity. Chromatin accessibility profiling and introgression scans identified cis-regulatory regions associated with discrete phenotypic switches. CRISPR perturbation of these regions in black hindwing genotypes recreated a yellow bar, revealing their spatially limited activity. In the H. melpomene/timareta lineage, the candidate CRE from yellow-barred phenotype morphs is interrupted by a transposable element, suggesting that cis-regulatory structural variation underlies these mimetic adaptations. Our work shows that cortex functionally controls scale colour fate and that its cis-regulatory regions control a phenotypic switch in a modular and pattern-specific fashion.



Evolution, developmental biology, Evolutionary Biology, Cis-regulation, Heliconius, Atac-seq, Wing Patterning, Crisppr

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Smithsonian Institution (NSF IOS-1656389)
National Science Foundation (IOS-1656553 and IOS-1755329, NSF IOS 1656389)
Biotechnology and Biological Sciences Research Council (BB/R007500/1)
Puerto Rico Science, Technology and Research Trust (#2020-00142)