Males and females can be under different evolutionary pressures if sexual and natural selection is differentially operating in each sex. As a result, many species have evolved sexual dichromatism, or differences in coloration between sexes. Although sexual dichromatism is often used as an index of the magnitude of sexual selection, sexual dichromatism is a composite trait. Here, we examine the evolution of sexual dichromatism in one of the largest and most ecologically diverse families of birds, the tanagers, using the avian visual perspective and a species-level phylogeny. Our results demonstrate that the evolutionary decreases of sexual dichromatism are more often associated with larger and more frequent changes in male plumage coloration, and evolutionary increases are not more often associated with larger changes in either sex. Furthermore, we show that the crown and ventral plumage regions are correlated with sexual dichromatism in males, and that only male plumage complexity is positively correlated with sexual dichromatism. Finally, we demonstrate that light environment is important in shaping both plumage brilliance and complexity. By conducting a multilevel analysis of plumage evolution in males and females, we show that sexual dichromatism evolves via a mosaic of sexual and natural selection in both sexes.
MCC phylogeny trimmed to data used in comparative analyses
MCC phylogeny from Burns et al. (2014). The tree has been trimmed to include the species used in comparative analyses. Citation: Burns, K. J., A. J. Shultz, P. O. Title, N. A. Mason, F. K. Barker, J. Klicka, S. M. Lanyon, and I. J. Lovette. 2014. Phylogenetics and diversification of tanagers (Passeriformes: Thraupidae), the largest radiation of Neotropical songbirds. MPE 75:41–77.
MCC_Tree_SpNames.nex
Posterior trees used in comparative analyses
Set of 100 phylogenies from the posterior distribution presented in Burns et al. (2014). The tree has been trimmed to include the species used in comparative analyses. Citation: Burns, K. J., A. J. Shultz, P. O. Title, N. A. Mason, F. K. Barker, J. Klicka, S. M. Lanyon, and I. J. Lovette. 2014. Phylogenetics and diversification of tanagers (Passeriformes: Thraupidae), the largest radiation of Neotropical songbirds. MPE 75:41–77.
Sampled_Tree_SpNames.nex
Phenotypic data
Phenotypic data used in comparative analyses, corresponding to supplemental tables 1-3. Headers are: SpeciesNumsCladesHab.csv – Information on each species measured for this study. For each species we give the number of species measured for each sex, presence or absence in the Thraupidae phylogeny, subfamily, habitat designation (F = closed/forest, N = open), foraging stratum (U = understory, C = canopy, U/C = both understory and canopy, N = open), maximum color span (MaxSexDich), average color span (AvgSexDich), Male combined, non-phylogenetic PC1 scores (MalePC1), female combined, non-phylogenetic PC1 scores (FemalePC1), male combined, non-phylogenetic PC2 scores (MalePC2), female combined, non-phylogenetic PC2 scores (FemalePC2), Male separate phylogenetic PC1 scores (MalePhyloPC1), Female separate phylogenetic PC1 scores (FemalePhyloPC1), Male separate phylogenetic PC2 scores (MalePhyloPC2), and Female separate phylogenetic PC2 scores (FemalePhyloPC2).
WPTCSmeasures.csv – All whole plumage tetrahedral color space measurements. The first two columns indicate species and sex, followed by average color span (AvgSpan), color span variance (VarSpan), maximum color span (MaxSpan), color volume (Volume), average hue disparity (AvgHueDisp), hue disparity variance (VarHueDisp), maximum hue disparity (MaxHueDisp), average brilliance (AvgBrill), average chroma (AvgChroma), and species abbreviations (species_abbr) to use with phylogenies.
AllTristimulusColorVariables_Translated.csv – All tri-stimulus color variables calculated for each measured region of each sex. We report the species abbreviation (see Supplemental Table 2 for full name), sex, region, theta, phi, r, and normalized brilliance (NormBrill).
PhenotypicData.zip
rtetracolorspace
This set of R scripts uses the set of functions implemented in tetracolorspace, a matlab package, (http://www.marycstoddard.com/#Software%20and%20tools) and implements them in R.
The reference for all analysis is: Stoddard, M. C., and R. O. Prum. 2008. Evolution of avian plumage color in a tetrahedral color space: a phylogenetic analysis of New World buntings. American Naturalist 171: 755–776.
Files:
RtcsFunctions.R: The source code for all functions.
ExampleScript.R: Examples and brief explanations of all rtcs functions.
bluetitss.dat: Spectral sensitivity data from the Blue Tit (obtained from tetracolorspace).
EunCamf_allpatches.csv: An example input data file of reflectance data taken from a female tanager.
visualization.R: A set of functions that can be used to visualize the tetracolorspace data.
R functions to perform Ancestral State Reconstructions of Color Cone Catches
Functions to replicate the analyses presented by Price and Eaton (2014). See comments in file for additional information.
Price, J. J., and M. D. Eaton. 2014. Reconstructing the evolution of sexual dichromatism: current color diversity does not reflect past rates of male and female change. Evolution 68:2026–2037.
PriceEaton2014AnalysisFunctions.R