Pigment concentrations and skin colour
Variation in skin colours was associated with the concentration of
pteridines but not carotenoids (Figure 4). Specifically,
redder skin hues (lower hue
values) were associated with higher drosopterin concentrations, and more
saturated colours were associated with higher xanthopterin, other
pteridines and total pteridine concentrations (Table 2). Tissues with
higher concentrations of other pteridines also had lower luminance
(darker). Yellow-red tissues (including browns, N=150) had higher
concentrations of drosopterin (Figure 4C), other pteridines, and
ketocarotenoids compared to black/grey/white tissues (N=36; 186 tissue
samples in total); whereas dietary carotenoid and xanthopterin
concentrations were similar in all skin colours (Table S4, Figure S2).
Additionally, skin luminance was associated with habitat productivity
(PC1 95% CIs 0.716 – 8.943), with darker colours in more vegetated
environments (Figure S3), but environmental PCs did not predict hue or
saturation (Table S5).