Ultraviolet reflectance accompanies classical aposematic palette in Delias butterflies (family: Pieridae)
Data files
Jun 25, 2026 version files 196.64 KB
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delias_spectro_package.zip
190.08 KB
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README.md
6.56 KB
Abstract
Ultraviolet (UV) reflectance has been widely documented in butterflies, primarily in the context of sexual signaling. Here we document, for the first time, the presence of UV-reflective pattern elements in multiple species of the aposematic pierid genus Delias. Importantly, these UV elements occur on the ventral wing surface and are spatially integrated within classical aposematic color patterns. We conducted a comparative survey across ~28 species and combined reflectance spectroscopy, chemical depigmentation of pterin scales, absorbance measurements, and microscopy to investigate the structural basis of this signal. Experimental removal of pterin pigments increased short-wavelength reflectance and produced UV reflectance visually similar to naturally occurring UV pattern elements. Microscopy revealed reduced pigment granulation in UV-reflective scales but did not detect highly ordered multilayer ridge architectures typical of scales reflecting iridescent UV in pierids. These findings indicate that UV reflectance in Delias is consistent with pigment-mediated modulation of broadband scattering of chitin rather than previously described iridescent multilayer interference. The experimental manipulation of pigment deposition demonstrates how modification of scale chemistry alters visual sensory output, highlighting a previously unrecognized component of aposematic coloration in this speciose genus.
Dataset DOI: 10.5061/dryad.m37pvmdht
Description of the data and file structure
The package titled "delias_spectro_package.zip" contains the data and code needed to reproduce the included processing/wrangling, statistical analyses, and plots for the manuscript titled "Ultraviolet Reflectance Accompanies Classical Aposematic Palette in Delias Butterflies (Family: Pieridae)".
Reflectance and absorbance data were collected from red, yellow, white, and two different ultraviolet-reflecting regions of Delias butterflies. Reflectance data was collected using a spectrophotometer. Absorbance data was collected by extracting pigments into a solution that was read by a nanodrop machine. Technical replicates were captured for both reflectance and absorbance and mean root mean squared error and mean correlation describe the low variance structure of the data. Below is the directory structure:
delias_spectro_pacakge.zip
Files and variables
File: delias_spectro_package
Description:
├───data
│ ├───reflection - each .txt file contains 5 technical replicate readings for the color noted in the file name.
│ │ CaeneusRedHW_Reflection__0__13-57-57-295.txt
│ │ CanaeusRedHW_Reflection__0__12-53-47-124.txt
│ │ CanaeusRedHW_Reflection__0__13-31-24-638.txt
│ │ CanaeusRedHW_Reflection__1__14-00-29-478.txt
│ │ DixeyiUVFW_Reflection__3__12-41-07-982.txt
│ │ DixeyiUVFW_Reflection__5__13-16-13-631.txt
│ │ DixeyiUVHW_Reflection__0__12-44-24-179.txt
│ │ DixeyiUVHW_Reflection__0__13-28-22-855.txt
│ │ DixeyUVFW_Reflection__0__13-46-40-122.txt
│ │ DixeyUVHW_Reflection__0__13-49-31-627.txt
│ │ HypareteWhiteFW_Reflection__0__13-01-04-691.txt
│ │ HypareteWhiteFW_Reflection__0__13-36-03-942.txt
│ │ HypareteWhiteFW_Reflection__0__14-04-38-201.txt
│ │ TimorensisYellowHW_Reflection__0__12-57-36-398.txt
│ │ TimorensisYellowHW_Reflection__0__13-33-45-124.txt
│ │ TimorensisYellowHW_Reflection__0__14-02-26-909.txt
│ │
│ └───absorbance - each .csv file contains either 5 or 6 technical replicate readings of the color for which the file is named.
│ yellow2_pterin.csv
│ red_pterin.csv
│ uvfw_pterin.csv
│ uvhw_pterin.csv
│ white_pterin.csv
│
├───code
│ spectro_2024.r - code used to generate plots and the metric summary .csv file.
.txt files are raw output generated by the ocean optics spectrophotometer and are most easily accessed using the R package "pavo". See the code file "spectro_2024.r" for handling the entire set of .txt reflection files.
All .txt files are structured as:
| Date | <date> |
|---|---|
| User | <user> |
| Spectrometer | FLMS19657 |
| Trigger mode | 0 |
| Integration Time | in seconds |
| Scans to average | 5 |
| Electric dark correction enabled | true |
| Nonlinearity correction enabled | false |
| boxcar width | 40 (sliding window of wavelengths) |
| XAxis mode | Wavelengths |
| Number of Pixels in Spectrum | 2048 |
| <Wavelength in nanometers> | <reflection reading in percent reflection> |
The .csv files are raw output from the nanodrop machine on the absorption setting. They are structured as:
| X | Y1 | Y2 | Y3 | Y4 | Y5 |
|---|---|---|---|---|---|
| wavelength (nm) | first reading | second reading | third reading | fourth reading | fifth reading |
Abbreviations:
uv = ultraviolet
fw = forewing
hw = hindwing
nm = nanometers
wl = wavelength
Spectral code analysis in R:
Reflection data was wrangled using the pavo R package which provides a tidy method of importing data from spectrophotometer .txt files. Stats reported (mean root mean squared error, mean correlation) were performed using base R functions. Absorbance data was additionally smoothed using the 'procspec()' function with span set to either '0.3' or '0.4'. Data smoothing removed noise induced by nanodrop absorbance readings.
Plotting was performed using ggplot2 package in R.
Code/software
Data files in .txt or .csv format may be imported into an R programming environment or read in microsoft word or libre office writer. No version requirements exist to access, navigate, or play with all data files. The reflection files are generated by the spectrophotometer machine (noted below) and represent percent reflectance, similarly, the nanodrop machine readings for absorbance values are also percent absorbance.
The code script ( "spectro_2024.r" ) contains all code used to reproduce plots and statistical analyses found in the manuscript. No version requirements, though, the code was run on R version 4.4.3 and used the pavo R package for importing reflection .txt files and smoothing absorbance data ( "procspec()" function). Plotting was performed using ggplot2.
R version used was R 4.4.3
Access information
Other publicly accessible locations of the data:
Data was derived from the following sources:
- Delias butterflies purchased through online distributors were used to acquire both reflectance (Ocean Optics FLAME-S-UV-VIS-ES spectrophotometer + Oceanview software) and absorbance (chemical extraction of pterin pigments -> nanodrop machine on absorbance setting) data.