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ABSTRACT The field of developmental biology has declined in prominence in recent decades, with off-shoots from the field becoming more fashionable and highly funded. This has created inequity in discovery and opportunity, partly due to the perception that the field is antiquated or not cutting edge. A ‘think tank’ of scientists from multiple developmental biology-related disciplines came together to define specific challenges in the field that may have inhibited innovation, and to provide tangible solutions to some of the issues facing developmental biology. The community suggestions include a call to the community to help ‘rebrand’ the field, alongside proposals for additional funding apparatuses, frameworks for interdisciplinary innovative collaborations, pedagogical access, improved science communication, increased diversity and inclusion, and equity of resources to provide maximal impact to the community. 

Long noncoding RNAs (lncRNAs) are transcribed elements increasingly recognized for their roles in regulating gene expression. Thus far, however, we have little understanding of how lncRNAs contribute to evolution and adaptation. Here, we show that a conserved lncRNA,ivory, is an important color patterning gene in the buckeye butterflyJunonia coenia.ivoryoverlaps withcortex, a locus linked to multiple cases of crypsis and mimicry in Lepidoptera. Along with a companion paper by Livraghi et al., we argue thativory, notcortex, is the color pattern gene of interest at this locus. InJ. coenia, a cluster ofcis-regulatory elements (CREs) in the first intron ofivoryare genetically associated with natural variation in seasonal color pattern plasticity, and targeted deletions of these CREs phenocopy seasonal phenotypes. Deletions of differentivoryCREs produce other distinct phenotypes as well, including loss of melanic eyespot rings, and positive and negative changes in overall wing pigmentation. We show that the color pattern transcription factors Spineless, Bric-a-brac, and Ftz-f1 bind to theivorypromoter during wing pattern development, suggesting that they directly regulateivory. This case study demonstrates howcis-regulation of a single noncoding RNA can exert diverse and nuanced effects on the evolution and development of color patterns, including modulating seasonally plastic color patterns. 

Evolutionary variation in the wing pigmentation of butterflies and moths offers striking examples of adaptation by crypsis and mimicry. Thecortexlocus has been independently mapped as the locus controlling color polymorphisms in 15 lepidopteran species, suggesting that it acts as a genomic hotspot for the diversification of wing patterns, but functional validation through protein-coding knockouts has proven difficult to obtain. Our study unveils the role of a long noncoding RNA (lncRNA) which we nameivory, transcribed from thecortexlocus, in modulating color patterning in butterflies. Strikingly,ivoryexpression prefigures most melanic patterns during pupal development, suggesting an early developmental role in specifying scale identity. To test this, we generated CRISPR mosaic knock-outs in five nymphalid butterfly species and show thativorymutagenesis yields transformations of dark pigmented scales into white or light-colored scales. Genotyping ofVanessa carduigermline mutants associates these phenotypes to small on-target deletions at the conserved first exon ofivory. In contrast,cortexgermline mutant butterflies with confirmed null alleles lack any wing phenotype and exclude a color patterning role for this adjacent gene. Overall, these results show that a lncRNA gene acts as a master switch of color pattern specification and played key roles in the adaptive diversification of wing patterns in butterflies. 

Although nearly phenotypically identical, few regulatory regions are conserved between two pairs of butterfly species. 

Ancient multifunctional regulatory elements underlie the evolution of butterfly wing color patterns.