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Impairment of mixed melanin-based pigmentation in parrots

Parrots and allies (Order Psittaciformes) have evolved an exclusive capacity to synthesize polyene pigments called psittacofulvins at feather follicles, which allows them to produce a striking diversity of pigmentation phenotypes. Melanins are polymers constituting the most abundant pigments in animals, and the sulphurated form (pheomelanin) produces colors that are similar to those produced by psittacofulvins. However, the differential contribution of these pigments to psittaciform phenotypic diversity has not been investigated. Given the color redundancy, and physiological limitations associated to pheomelanin synthesis, this study assumed that the latter would be avoided by psittaciform birds. This hypothesis was tested by using Raman spectroscopy to identify pigments in feathers exhibiting colors suspicious of being produced by pheomelanin (i.e., dull red, yellow and grey- and green-brownish) in 26 species from the three main lineages of Psittaciformes. The non-sulphurated melanin form (eumelanin) were detected in black, grey and brown plumage patches, and psittacofulvins in red, yellow and green patches, but no evidence of pheomelanin was found. As natural melanins are assumed to be composed of eumelanin and pheomelanin in varying ratios, these results represent the first report of impairment of mixed melanin-based pigmentation in animals. Given that psittaciforms also avoid the uptake of circulating carotenoid pigments, these birds seem to have evolved a capacity to avoid functional redundancy between pigments, likely by regulating follicular gene expression. The study provides the first vibrational characterization of different psittacofulvin-based colors and thus helps to determine the relative polyene chain length in these pigments, which is related to their antireductant protection activity. informacion[at]ebd.csic.es: Neves et al (2020) Impairment of mixed melanin-based pigmentation in parrots. J Experim Biol. DOI 10.1242/jeb.225912


https://jeb.biologists.org/content/early/2020/05/08/jeb.225912
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Mirror, mirror! Where should I settle?

Mirror, mirror! Where should I settle?

The matching habitat choice hypothesis holds that individuals with different phenotypes select the habitats to which they are best adapted to maximize fitness. Despite the potential implications of matching habitat choice for many ecological and evolutionary processes, very few studies have tested its predictions. Here, a 26-year dataset on a spatially structured population of pied flycatchers is used to test whether phenotype-dependent dispersal and habitat selection translate into increased fitness (recruitment success). In this study system, males at the extremes of the body size range segregate into deciduous and coniferous forests through nonrandom dispersal. According to the matching habitat choice hypothesis, fitness of large males is expected to be higher in the deciduous habitat, where they preferentially settle to breed, while the reverse would be true for small males, which are more frequent in the coniferous forest. In the coniferous forest, males at the middle of the size range had higher fitness than both large and small-sized males. However, no clear trend was observed in the deciduous forest, where males of either size had similar fitness. These results do not provide positive support for the hypothesis' predictions and, therefore, a conclusive demonstration of its operation and occurrence in nature remains to be done. informacion[at]ebd.csic.es: Camacho et al (2015) Testing the matching habitat choice hypothesis in nature: phenotype-environment correlation and fitness in a songbird population. Evol Ecol 29: 873–886; DOI 10.1007/s10682-015-9793-4


http://link.springer.com/article/10.1007/s10682-015-9793-4