DOI: 10.5061/dryad.stqjq2cb8
title: Data from: Thermal plasticity in protective wing pigmentation is modulated by genotype and food availability in an insect model of seasonal polyphenism

description: Phenotypic variation in natural populations results from complex
 interactions between organisms and their changing environments. The
 environment shapes both phenotypic frequencies (during adaptation) and
 organismal phenotypes (through phenotypic plasticity). Developmental
 plasticity, in particular, refers to the phenomenon whereby an organism’s
 phenotype depends on the environmental conditions during development. It
 can match phenotype to ecological conditions and help organisms to cope
 with environmental heterogeneity, including differences between
 alternating seasons. Experimental studies of developmental plasticity
 often focus on the impact of individual environmental cues and do not take
 explicit account of genetic variation. In contrast, natural environments
 are complex, comprising multiple variables with combined effects that are
 poorly understood and may vary among genotypes. We investigated the
 effects of multifactorial environments on the development of the
 seasonally plastic eyespots of Bicyclus anynana butterflies. Eyespot size
 depends on developmental temperature and is involved in alternative
 seasonal strategies for predator avoidance. In nature, both temperature
 and food availability undergo seasonal fluctuations. However, our
 understanding of how thermal plasticity in eyespot size varies in response
 to food availability and across genotypes remains limited. To address
 this, we investigated the combined effects of temperature (T; two levels:
 20°C and 27°C) and food availability (N; two levels: control and limited)
 during development. We examined their impact on wing and eyespot size in
 adult males and females from multiple genotypes (G; 28 families). We found
 evidence of thermal and nutritional plasticity and
 temperature-by-nutrition interactions (significant TxN) on the size of
 eyespots in both sexes. Food limitation resulted in relatively smaller
 eyespots and tempered the effects of temperature. Additionally, we found
 differences among families for thermal plasticity (significant GxT
 effects), but not for nutritional plasticity (non-significant GxN effects)
 nor for the combined effects of temperature and food limitation
 (non-significant GxTxN effects). Our results reveal the context dependence
 of thermal plasticity, with the slope of thermal reaction norms varying
 across genotypes and across nutritional environments. We discuss these
 results in light of the ecological significance of pigmentation and the
 value of considering thermal plasticity in studies of the biological
 impact of climate change.
description: For this study we used <em>B. anynana</em> specimens
 from a previous full-factorial split-brood experiment (doi:
 10.1002/ece3.718) examining variation in various life-history traits in
 relation to two thermal environments, two nutritional treatments, and 28
 families (corresponding to different genotypes). An image of one wing of
 each individual was analysed with custom Mathematica notebooks that
 allowed the definition and measurement of a wing transect, which we used
 as a proxy for wing size, and of the diameter of the eyespot included in
 that transect, which we used as our measurement of eyespot size. We tested
 the effects of genotype, temperature, and nutrition, as well as
 interactions between them on eyespot size, with wing size as covariate. We
 also calculated and analysed the slopes of the thermal and nutritional
 reaction norms for eyespot size. More details can be found in the
 Materials and Methods section of the paper these data correspond
 to.
description: # Thermal plasticity in protective wing pigmentation is modulated by
 genotype and food availability in an insect model of seasonal polyphenism.
 [https://doi.org/10.5061/dryad.stqjq2cb8](https://doi.org/10.5061/dryad.stqjq2cb8) ## Description of the data and file structure Our experimental animals include female and male progeny (variable “sex” with F or M, respectively) from 28 families (variable “genotype” with identification number of the family) reared at one of two temperatures (variable “temperature” with 20 or 27 corresponding to 20°C or 27°C, respectively) and one of two food quantity treatments (variable “nutrition” with “control” or “limited”). An image of one wing of each individual was analyzed with custom Mathematica notebooks that allowed the definition and measurement of a wing transect, which we used as a proxy for wing size, and of the diameter of the eyespot included in that transect, which we used as our measurement of eyespot size. Measurements were obtained as number of pixels and converted to millimeters. The variables “wing_pixels” and “eyespot_pixels” correspond to wing and eyespot size, respectively, in pixels. The variables “wing_mm” and “eyespot_mm” correspond to wing and eyespot size, respectively, in millimetres. The variable “relative_eyespot” corresponds to the ratio of eyespot size / wing size. We correlated our measurement of wing size with two other body size measurements obtained in a previous study of the same individuals (doi: 10.1002/ece3.718): “pupal_weight_g” referring to pupal weight in grams, and “adult_dry_weight_g” referring to adult dry weight in grams. ## Code/Software A file with the R code used for data  analysis was provided as supplementary file S3 of the paper reporting on these data.