Content with tag plumage coloration .

A source of exogenous oxidative stress improves oxidative status and favors pheomelanin synthesis in zebra finches

Some organisms can modulate gene expression to trigger physiological responses that help adapt to environmental stress. The synthesis of the pigment pheomelanin in melanocytes seems to be one of these responses, as it may contribute to cellular homeostasis. Environmental oxidative stress was experimentally induced in male zebra finches Taeniopygia guttata by the administration of the herbicide diquat dibromide during feather growth to test if the expression of genes involved in pheomelanin...

Juvenile pheomelanin-based plumage colouration has evolved more frequently in carnivorous species

Distinctive pheomelanin-based plumage colouration in juvenile birds has been proposed as a signal of immaturity to avoid aggression by older conspecifics, but recent findings suggest a detoxifying strategy. Pheomelanin synthesis implies the consumption of cysteine, a semi-essential amino acid that is necessary for the synthesis of the antioxidant glutathione (GSH) but that may be toxic if in excess in the diet.

A negative association between melanin-based plumage color heterogeneity and intensity in birds

Even though plumage diversity is one of the most diverse phenotypic traits in nature, the reasons why some species exhibit more distinctive colors than others are poorly known. In the case of melanins, different chemical forms lead to different plumage colors and different amounts of those forms lead to different color intensities. However, the synthesis of some melanin forms is more physiologically limited than others. Here, authors hypothesize that an evolutionary solution to this scenario...

Physiological compartmentalization as a possible cause of phylogenetic signal loss: an example involving melanin-based pigmentation

Phylogenetic signal is the extent to which phenotypic expression is related to phylogenetic relationships between species, thus reflecting the effect of common ancestry. Signal loss occurs when some species obtain adaptation, regarding a given trait, to certain environmental conditions. Compartmentalization in processes leading to trait expression reduces dependence among them, thus favoring, up to some degree, their independent evolution. Compartmentalization may therefore lead to...

Dynamic signalling in the greater flamingo

Colourful plumage is typical of males in species with conventional sex roles, in which females care for offspring and males compete for females, as well as in many monogamous species in which both sexes care for offspring. Reversed sexual dichromatism—more colourful females than males—is predominant in species with sex role reversal. In the latter species, males care for offspring and females compete for mates, the mating system is mainly polyandrous and there is reversed size...