Meeting Abstract
The vast array of biodiversity and natural variation that we see around us has been generated through a combination of genetic and environmental influences. Butterfly wing coloration provides an attractive evolutionary model to study the role of these interactions throughout development. Here we have I.) Characterized the developmental plasticity of pigment (pink) and structural (Ultraviolet) butterfly wing colors, II.) Investigated the environmental triggers responsible for both colors, III.) Examined a potential ecological significance of the pink polyphenism and IV.) Tested a candidate gene from the melanin pathway generating the polyphenetic variation. Through collections we demonstrate the seasonal polyphenism in both pterin pigmentation and UV structural coloration on Zerene cesonia wings. Our results show that both photoperiod and temperature are necessary for the induction of both color changes, but the threshold for the change to pink is sexually dimorphic. Characterizations revealed scale level organizational and morphological changes throughout the pink morphs. We have evidence suggesting that the pink coloration may be caused by an increase in melanin, which is supported by thermal measurements showing that winter morphs warm faster than summer morphs. Lastly, we show, using CRISPR/ cas9, that knockouts of the eyespot melanin gene Spalt can partially induce the pink phenotype when grown in summer conditions. Spalt knockouts recapitulate the pink phenotype in both pigment and morphological changes. Overall this work suggests that there may be a shared environmental and developmental mechanism between pigment and structural coloration in the Southern Dogface Butterfly
