Fig 1.
Molleweide projection of the 2100 color patches used in this study when perceived by an average UVS visual system under ideal illumination.
The colors of the symbols are approximations of the colors of the patches based on a human visual system. SWS1, SWS2, MWS, and LWS refer to the ultraviolet-, short-, medium-, and long-wavelength photoreceptor, respectively.
Table 1.
Parameters used to reproduce the average VS and average UVS avian visual systems presented in Endler and Mielke (2005).
Fig 2.
Effect of the ocular media parameter on calculated sexual dichromatism scores.
Comparison of the A) mean sexual dichromatism scores (in JNDs), and B) sexual dichromatism ranks of 70 galliform species for a UVS eye type with different ocular media transmission. Values on the x-axis were generated by setting the T50 of the ocular media at 314 nm (see formulae in S2 File) and the values on the y-axis were generated by setting the T50 of the ocular media at 344 nm. The solid triangle symbol in A) identifies the species that experienced the greatest change in mean dichromatism score, and the greatest change in rank in B). The sexual dichromatism score of each patch of the species highlighted in A), under the two sets of parameters, are presented in C). The sexual dichromatism score of each patch of the species highlighted in B), under the two sets of parameters, are presented in D). In C) and D), the solid triangle symbol identifies the patch that experienced the greatest change in dichromatism score. Dashed lines represent 1:1 reference line.
Fig 3.
Effect of the photoreceptor density parameter on calculated sexual dichromatism scores.
Comparison of A) the mean sexual dichromatism scores (in JNDs), and B) ranks of 70 galliform species for a UVS eye type with different photoreceptor densities. Values on the x-axis were generated using the parameters associated with the ‘average UVS eye-type’ visual system but with the photoreceptor densities found in Anous minutus (SWS1–1.00, SWS2–9.59, MWS– 16.82, LWS– 14.29); values on the y-axis were generated with the ‘average UVS eye-type’ visual system but with the photoreceptor densities found in Puffinus pacificus (SWS1–1.00, SWS2–0.68, MWS– 1.04, LWS– 1.44; see Methods). The solid triangle symbol in A) identifies the species that experienced the greatest change in mean dichromatism score, and the greatest change in rank in B). The sexual dichromatism score of each patch of the species highlighted in A), under the two sets of parameters, are presented in C). The sexual dichromatism score of each patch of the species highlighted in B), under the two sets of parameters, are presented in D). In C) and D), the solid triangle symbol identifies the patch that experienced the greatest change in dichromatism score. Dashed lines represent 1:1 reference line.
Fig 4.
Effect of using either the UVS or VS average eye-type on calculated sexual dichromatism scores.
Comparison of A) the mean sexual dichromatism scores (in JNDs), and B) ranks of 70 galliform species contrasting the two most commonly used bird visual systems. Values on the x-axis were generated using the parameters associated with the ‘average UVS eye-type’ visual system; values on the y-axis were generated with the ‘average VS eye-type’ visual system (see Methods). The solid triangle symbol in A) identifies the species that experienced the greatest change in mean dichromatism score, and the greatest change in rank in B). The sexual dichromatism score of each patch of the species highlighted in A), under the two sets of parameters, are presented in C). The sexual dichromatism score of each patch of the species highlighted in B), under the two sets of parameters, are presented in D). In C) and D), the solid triangle symbol identifies the patch that experienced the greatest change in dichromatism score. Dashed lines represent 1:1 reference line.
Table 2.
Summary of the visual system comparisons that generated the largest differences, based on the lowest Pearson’s r value, in the mean dichromatism scores of 70 species of the Order Galliformes.
Table 3.
Summary of the changes in dichromatism score of the species most affected by changes in the sensory exprience, based on the absolute largest difference in mean dichromatism score.
Table 4.
Summary of the changes in dichromatism score of the species most affected by changes in the sensory exprience, based on the largest difference in rank.
Fig 5.
Range of sexual dichromatism scores of three galliform species obtained through exploration of the multidimensional parameter space.
Distribution of mean dichromatism scores (left panels) and number of patches (out of 15) with scores greater than 1 JND (right panels), for three species, generated through permutation of all parameter conditions explored in this study (see Multidimensional parameter space section in Methods). Lines for average UVS eye type, average VS eye type, and Pavo cristatus indicate values calculated under an ideal illuminant.