Effects of PcG gene knockdowns on adult morphology

Aposematic coloration offers an opportunity to explore the molecular mechanisms underlying canalization. In this study, the role of epigenetic regulation underlying robustness was explored in the aposematic coloration of the milkweed bug, Oncopeltus fasciatus. Polycomb (Pc) and Enhancer of Zeste (E(z)), which encode components of the Polycomb Repressive Complex 1 (PRC1) and PRC2, respectively, and jing, a component of the PRC2.2 subcomplex, were knocked down in the fourth instar of O. fasciatus. Knockdown of these genes led to alterations in scutellar morphology and melanization. In particular, when Pc was knocked down, the adults developed a highly melanized abdomen, head, and forewings at all temperatures examined. In contrast, the E(z) and jing knockdown led to increased plasticity of the dorsal forewing melanization across different temperatures. Moreover, jing knockdown adults exhibited increased plasticity in the dorsal melanization of the head and the thorax. These observations d..., Oncopeltus fasciatus 4th instar nymphs were injected with 1 μg (0.5 μL) of ampicillin resistance, Polycomb (Pc), Enhancer of zeste (E(z)) and jing double-stranded RNA using a syringe and a pulled borosilicate needle. The nymphs were reared at 20°C, 26.5°C or 33°C. Whole bodies of adult O. fasciatus were kept frozen at -20°C. The ventral abdomen of each bug was fixed in 3.7% formaldehyde and mounted in a 70% glycerol:30% PBS solution or an 80% glycerol:20% water solution and then imaged. Adult bugs were imaged under a Leica M165 FC stereo microscope and images were captured using a Leica DFC310 FX camera. Images were analyzed using the ImageJ software., , # Effects of PcG gene knockdowns on adult morphology

[https://doi.org/10.5061/dryad.f7m0cfz51](https://doi.org/10.5061/dryad.f7m0cfz51)

In this study, the role of epigenetic regulation underlying robustness was explored in the aposematic coloration of the milkweed bug, *Oncopeltus fasciatus*. *Polycomb* (*Pc*), *Enhancer of Zeste* (*E(z)*) and *jing* were knocked down in the fourth instar of *O. fasciatus* and the adult morphology was analyzed. The data provided are measurements made on individual adult bugs that were used to generate the graphs in the manuscript.

## Description of the data and file structure

**1. Wing_measurements:** This file includes the area of the forewings, the length of the forewings and the width of the forewings of individual bugs as shown in Supplemental Figure S2. The ratio of length/width was calculated by dividing the length by the width. Measurements were obtained from adults that were injected with *ampr*, *E(z)*, *jing* or *Pc* dsRNA during the 4th i...