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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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Context dependence of road-use behaviours

Context dependence of road-use behaviours

Many animals avoid roads due to traffic disturbance, but there are also some species that use roads in their everyday life and even obtain resources from them. Understanding the factors that influence the intensity of road use by these species can help understand temporal patterns of road mortality and thereby maximize the cost-effectiveness of mitigation measures. This study, conducted between 2009 and 2017 in Doñana, investigates the environmental factors influencing road use in the red-necked nightjar Caprimulgus ruficollis, a nocturnal insectivorous bird that frequents roads to forage and thermoregulate. Nightjar abundance on roads was affected by ambient temperature, amount of moonlight, and wind conditions, all factors known to influence their foraging efficiency and thermoregulatory requirements. Specifically, the highest numbers of nightjars on roads occurred during no-wind conditions and on either dark-cold or bright-warm nights, suggesting that they preferentially use roads (i) for thermoregulation under unfavourable weather conditions or (ii) to maximize food intake during periods of increased insect abundance (warm nights) and improved conditions for visual prey detection (full moon). These results illustrate the role of environmental conditions as drivers of rapid changes in the use of roads by animals and suggest that analogous studies can be used to inform mitigation measures, so that mitigation efforts to prevent roadkills can be concentrated during periods of expected peaks in animal use of roads. informacion[at]ebd.csic.es: De Felipe et al. (2019) Environmental factors influencing road use in a nocturnal insectivorous bird. Eur J Wildl Res https://doi.org/10.1007/s10344-019-1267-5


https://link.springer.com/article/10.1007/s10344-019-1267-5