Data for: Ebony underpins Batesian mimicry in melanic stoneflies

The evolution of Batesian mimicry – whereby harmless species avoid predation through their resemblance to harmful species – has long intrigued biologists. In rare cases, Batesian mimicry is linked to intraspecific colour variation, in which only some individuals within a population resemble a noxious ‘model’. Here, we assess intraspecific colour variation within a widespread New Zealand stonefly, wherein highly melanised individuals of Zelandoperla closely resemble a chemically defended aposematic stonefly, Austroperla cyrene. We assess convergence in the colour pattern of these two species, compare their relative palatability to predators, and use genome-wide association mapping to assess the genetic basis of this resemblance. Our analysis reveals that melanised Zelandoperla overlap significantly with Austroperla in colour space, but are significantly more palatable to predators, implying that they are indeed Batesian mimics. Analysis of 194,773 genome-wide SNPs reveals an outlier locu..., Photographs were taken in RAW format using a Canon 40D camera with an EF-S 60 mm f/2.8 lens under fixed magnification, exposure time, aperture, and ISO sensitivity settings. The average red, green, and blue (RGB) colour channel values of each image were then linearised and equalised in reference to the nominal RGB values of the grey patches of the ColorGauge Pico target in Adobe Photoshop CC 2021. Colour measurements were taken from calibrated images in five regions of interest (ROIs) using the RGB Measure function in ImageJ. The first three chosen ROIs correspond to areas of the head (1), pronotum (2), and femorae (3), to provide a broad representation of overall body melanisation. The additional ROIs correspond to areas on the foreleg tibiae (4) and forewing bases (5) associated with warning colouration in the aposematic model Austroperla. Mean RGB values from each ROI were converted to HSB (hue, saturation, brightness) values using the colorsys module in Python, and only the achromat..., , ## Data for: ebony underpins Batesian mimicry in melanic stoneflies

This dataset contains colour measurement data for 338 Zelandoperla fenestrata and 22 Austroperla cyrene stonefly specimens.

Photographs were taken in RAW format using a Canon 40D camera with an EF-S 60 mm f/2.8 lens under fixed magnification, exposure time, aperture, and ISO sensitivity settings. The average red, green, and blue (RGB) colour channel values of each image were then linearised and equalised in reference to the nominal RGB values of the grey patches of the ColorGauge Pico target in Adobe Photoshop CC 2021. Colour measurements were taken from calibrated images in five regions of interest (ROIs) using the RGB Measure function in ImageJ. The first three chosen ROIs correspond to areas of the head (1), pronotum (2), and femorae (3), to provide a broad representation of overall body melanisation. The additional ROIs correspond to areas on the foreleg tibiae (4) and forewing bases (5) associated with warning co...