Animals cannot synthesize carotenoid pigments de novo, and must consume them in their diet. Most mammals, including humans, are indiscriminate accumulators of carotenoids but inefficiently distribute them to some tissues and organs. To date, no mammal has been known to have evolved physiological mechanisms to incorporate and deposit carotenoids in the skin or hair. Here it is shown that the Honduran white bat colors its skin bright yellow with the deposition of the xanthophyll lutein.

In ground-nesting birds egg colour and appearance may have evolved due to opposite selection pressures. Pigmentation and spottiness make the eggs darker and have been suggested to improve camouflage. However these eggs may reach higher temperatures, which may be lethal for embryos. Some authors suggested that this trade-off may not exist. In this study the occurrence of a trade-off between camouflage and overheating of eggs is tested.

Knowledge of melanin chemistry has important implications for the study of the evolutionary ecology of animal pigmentation, but the actual chemical diversity of these widely expressed biological pigments has been largely overlooked.