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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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Downsized mutualisms: Consequences of seed dispersers’ body-size reduction for early plant recruitment

Downsized mutualisms: Consequences of seed dispersers' body-size reduction for early plant recruitment

Human-driven body-size reduction of frugivorous vertebrates may entail the loss of seed dispersal functions, impairing plant regeneration. Here, the consequences of body-size reduction of Giant Canarian lizards (g. Gallotia, Lacertidae) on the recruitment of Neochamaelea pulverulenta (Rutaceae), an endemic shrub relying exclusively on these frugivores for seed dispersal, are evaluated. Results show that the age structure patterns (quantitative component) did not differ, but significant reductions in effective recruitment rate, and seedling vigour in populations hosting small- to medium-sized lizard species, are found. Results highlight the importance of conserving the full range of functional processes (qualitative and quantitative components) involved in mutualistic interactions crucial for the persistence of local regeneration and plant population dynamics. informacion[at]ebd.csic.es Pérez-Méndez et al (2015).  Downsized mutualisms: Consequences of seed dispersers' body-size reduction for early plant recruitment. Perspect Plant Ecol Evol Syst DOI: 10.1016/j.ppees.2014.12.001