(a) The ratio of dihydrogalloxanthin to total apocarotenoid content in the whole retina differs between UV and VS species. Each point represents a different species, and the bar indicates the mean for each visual system. (b) The UV-Vis absorbance spectrum of the expanded C-type oil droplets of selected UVS and VS species, and (c) the spectrum of galloxanthin and dihydrogalloxanthin for comparison. (d–g) The mean ± S.D. proportion of each carotenoid in the additive mixture of pure spectra that best fits the C-type droplet spectra from (d) chicken (n = 5, VS), (e) mallard (n = 3, VS), (f) zebra finch (n = 5,UVS), and (g) house finch (n = 4, UVS). The pure carotenoid spectra, the observed C-type droplet spectra, and the fitted spectra of each droplet used to estimate oil droplet composition are presented in Figure 3—figure supplement 2.
DOI:
http://dx.doi.org/10.7554/eLife.15675.010
Figure 3—source data 1. The measured oil droplet spectra, pure carotenoid spectra, and model fit parameters for each measured C-type droplet.