Data from: Predation risk determines pigmentation phenotype in nuthatches by melanin-related gene expression effects

Pigments determine the appearance of organisms. However, pigment
production can be associated to physiological constraints as in the case
of pheomelanin, the sulphurated form of melanin whose synthesis in
melanocytes consumes cysteine and consequently reduces the availability of
glutathione (GSH) to exert antioxidant protection. Pheomelanogenesis may
thus increase the susceptibility to suffer chronic oxidative stress. I
investigated the possibility that environmental lability in the expression
of genes regulating pheomelanogenesis protects from oxidative stress, a
situation in which GSH is most required. By broadcasting adult alarm
calls, I manipulated the perception of predation risk, a natural source of
oxidative stress, in free-living Eurasian nuthatch Sitta europaea
nestlings developing pheomelanin-pigmented flank feathers. The
manipulation affected the consumption of GSH that resulted from the
expression of two genes (Slc7a11 and Slc45a2) influencing cysteine/GSH
availability in cells, as these genes were downregulated in the feather
melanocytes of the nestlings with lowest intracellular antioxidant
capacity (i.e., lowest GSH levels). Systemic oxidative damage increased
with Slc7a11 expression in feather melanocytes, suggesting that the
observed downregulation was physiologically advantageous. The nestlings
exposed to an increased perception of predation risk developed flank
feathers of reduced color intensity. These results indicate that perceived
predation risk can determine the pigmentation phenotype by (probably
epigenetic) effects on gene expression that protect from physiological
constraints imposed by pheomelanin production.