Original title: No evidence that carotenoid pigments boost either immune or antioxidant defenses in a songbird
CarotenoidsPigments found in food and animal tissues that can contribute to yellow, orange, or red colors. are pigments that help give some birds their color. Researchers compared yellow canaries, which have high carotenoid levels in their tissues, with white canaries whose mutation leaves them with very low levels. They exposed both groups to challenges involving harmful microbes and cell damage, then measured how their bodies performed. Across the measures they used, the groups did not differ.
Imagine two people doing the same kitchen clean-up after a spill. One has a brightly colored sponge and the other has a pale one, but both get the same mess and tools. It is hard to tell whether the color itself helps unless you compare how well they clean. In this paper, the two sponges are the canary groups, the spill is the bodily challenge, and the researchers find no difference in how well they handle it.
People often assume that the pigments behind bright yellow feathers also help birds fight infection or cell damage. These results challenge that idea: in the canaries tested, high tissue carotenoid levels did not mean stronger measured defenses.
The abstract reports no differences across the physiological measures used in these canaries under the challenges tested. It does not establish that carotenoids have no effects in every bird, under all conditions, or on every physiological process. It also notes that some dietary carotenoids may have indirect benefits as retinoid precursors.
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No evidence that carotenoid pigments boost either immune or antioxidant defenses in a songbird — Rebecca E. Koch, Andreas N. Kavazis, Dennis Hasselquist et al. — Nature Communications — doi:10.1038/s41467-018-02974-x
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.