DOI: 10.5061/dryad.vhhmgqnpx
title: Data from: Background matching, disruptive coloration and differential use of microhabitats in two neotropical grasshoppers with sexual dichromatism

description: Cryptic coloration is an adaptative defensive mechanism against predators.
 Color patterns can become cryptic through background coloration-matching
 and disruptive coloration. Disruptive coloration may evolve in visually
 heterogeneous microhabitats, whereas background matching could be favored
 in chromatically homogeneous microhabitats. In this work, we used digital
 photography to explore the potential use of disruptive coloration and
 background matching in males and females of two grasshopper species of the
 Sphenarium genus in different habitats. We found chromatic differences in
 the two grasshopper species that may be explained by local adaptation. We
 also found that the females and males of both species are dichromatic and
 seem to follow different color cryptic strategies, males are more
 disruptive than females, whereas females have a high background matching
 with less disruptive elements. The selective pressures of the predators in
 different microhabitats and the differences in mobility between sexes may
 explain the color pattern divergence between females and males.
 Nevertheless, more field experiments are needed in order to understand the
 relative importance of disruptive and background matching coloration in
 the evolution of sexual dichromatism in these grasshoppers.
description: <strong><em>Pattern
 analysis</em></strong> We
 performed a granularity analysis based on the Fast Fourier bandpass
 filtering to evaluate the color patterns. Bandpass filters allow
 information at different spatial scales to be separated (for details see
 Chiao <em>et
 al.</em>, 2009;
 Stoddard and Stevens, 2010). We used the average pixel reflectance of red and
 green channels to calculate the energy spectrum of grasshoppers and their
 background across 15 filters ranging from 2 pixels to 256 pixels, in
 increments of multiples of √2. We obtained three descriptive variables
 from the energy spectrum: the maximum energy peak of the spectrum
 (e<sub>max</sub>), the filter size where
 e<sub>max</sub> is reached
 (Filter<sub>max</sub>), and the proportion of the
 e<sub>max</sub> compared to the rest of the spectrum
 (e<sub>prop</sub>), which respectively indicate contrast of the
 dominant marking, marking size and pattern diversity. <strong><em>Color background matching
 analysis</em></strong> Color
 background matching was evaluated by measuring individual pixel
 reflectance and calculating the mean reflectance values of the
 multispectral image for the three channels (RGB) for the grasshoppers and
 their backgrounds. Spectral images are in a 16-bit scale, given this image
 format, the reflectance values range from zero to
 65535. <strong><em>Disruptive
 coloration</em></strong> We
 evaluated the edge disruption of grasshoppers using GabRat tool
 implemented in MICA toolbox. GabRat tool measured the ratio between false
 and coherent edges of the grasshoppers’ surfaces. For the GabRat analysis we use the multispectral
 image used in the granularity analysis. We obtained the GabRat values from
 the photographs of grasshoppers’ dorsal surface. For this analysis the
 size of the Gabor filter (sigma) ideally should match the acuity of the
 possible viewers in order to be effective. In this study we use a sigma
 value = 5 because it has been informative in analysis where the objects
 were scaled close to 17 pixels per mm (Troscianko, Skelhorn and Stevens, 2018; Price
 <em>et
 al.</em>,
 2019). We
 obtained the GabRat value for R, G, B channels of the multispectral
 images, subsequently we obtained the mean GabRat ( average GabRat) of the three channels for every
 grasshoppers’ photograph.
description: Excel file contains: Table S1. Data for the
 pattern analysis.<br> Table S2. Data for the color means
 analysis.<br> Tabla S3. Data for the coloration disruptive
 analysis.