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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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Loss of pollinators: evidences, causes and consequences

Loss of pollinators: evidences, causes and consequences

Over the past few years discussions on the pollinator crisis have increased and campaigns to save bees have multiplied. However, these campaigns have not always been evidence-based. During the last years, also research on this topic has substantially increased and our knowledge about the causes and consequences of the current loss of pollinators has reached an important maturity. This monograph reviews the importance of pollinators, their main threats and what consequences the decline of their populations can have for ecosystems. In addition, given the enormous diversity of pollinators, and especially bees, in the Iberian Peninsula, it is particularly important to deal with this issue from an Iberian perspective. The climatic, geographical and socio-cultural peculiarities of this region make it often difficult to extrapolate results obtained in temperate zones of northern Europe or the United States, two areas overrepresented in terms of research. More precisely, in this monograph the natural history of pollinators in Spain has been reviewed, revealing the clear lack of knowledge about the status of pollinator populations. Additionally, several causes of the decline of pollinators are identified, of which some show interactions, being the main cause probably habitat loss. Finally, the consequences of pollinator loss on the functioning of ecosystems are reviewed, not only for agricultural production, but also for wild flora, both from an ecological and evolutionary perspective. informacion[at]ebd.csic.es: Bartomeus & Bosch (2018) Eds. Monográfico Pérdida de polinizadores: evidencias, causas y consecuencias. Ecosistemas 27(2) Doi 10.7818/ECOS.2018.27-2


https://www.revistaecosistemas.net/index.php/ecosistemas/issue/view/55