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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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Analysis of the effects of an extreme climatic event on scrub communities

Analysis of the effects of an extreme climatic event on scrub communities

The effects of an extreme climatic event on shrub species were assessed by analyzing their leaves, roots, seeds and stem. In 2005, very low temperatures were recorded during winter (-6 ºC) together with the lowest historical rainfall annual record (217 mm). Both situations of climatic stress dramatically affected the plant communities of the Doñana Monte Blanco's ecosystem, despite being a plant community specially adapted to summer drought. The long-term monitoring of scrub communities allowed to evidence the effects of this extreme event by monitoring the permanent network of plots sampled annually and the remote sensing images. The results showed, first, that not all scrub species respond in a similar way showing a wide gradient of affection. Secondly, these differences are clearly in relation to the various functional traits of the plants. The 2005 drought reduced the vegetation cover by 50 percent for three of the most common species. The figure is alarming considering that these scrubs are specially adapted to drought. After six years, the species composition varied slightly but the vegetation cover was restored almost completely. In general, the Doñana community scrub was shown as quite resilient. Plant species with roots of higher density and diameter are generally more conservative, less wasteful in the water use at the expense of having a slower growth. Species having sclerophyll leaves and roots show up as a recurring strategy among Mediterranean woody species to combat the shortage of water and nutrients. informacion[at]ebd.csic.es: Lloret et al (2016) Climatic events inducing die-off in Mediterranean shrublands: are species' responses related to their functional traits? Oecologia DOI 10.1007/s00442-016-3550-4


http://link.springer.com/article/10.1007%2Fs00442-016-3550-4