Siegel, Kate2022-11-172022-11-172022-11-17https://hdl.handle.net/1813/112200Despite the great beauty and diversity of butterfly wing color patterns, there is still much that remains unknown about how these color patterns are determined. Certain master regulator genes are known that can determine the scale type or pigment across a variety of color pattern elements, and their expression is determined through the combined activity of upstream pre-patterning genes. For one such key gene, optix, most of its regulatory network is still unknown, though candidates have been proposed. This study aims to take a closer look at the functions of one candidate upstream gene, araucan, a proximally expressed transcription factor that plays a role in wing vein specification in Drosophila. Using CRISPR-Cas9 gene editing, mutations were induced in the araucan gene in two nymphalid butterfly lineages, Junonia coenia and two co-mimetic species of Heliconius. Examining wings for phenotypes revealed some optix-typical mutations such as bright blue structural iridescence across J. coenia wings, as well as vein reductions in H. erato that suggest the function of araucan may be partially conserved relative to Drosophila. An unexpected novel phenotype affecting the iridescence of the eyespot center, or focus, also appeared, introducing a potential role for araucan in eyespot color patterning.en-USAttribution-NonCommercial-NoDerivatives 4.0 Internationalgene regulationwing patterningaraucanoptixCRISPRdissertation or thesis