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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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Benefits of restoring apex predator populations

Benefits of restoring apex predator populations

The role that apex predators play in ecosystem functioning, disease regulation and biodiversity maintenance is increasingly debated. However, the positive impacts of their presence in terrestrial ecosystems, particularly in human-dominated landscapes, remain controversial. Limited experimental insights regarding the consequences of apex predator recoveries may be behind such controversy and may also impact on the social acceptability towards the recovery of these species. Using a quasi-experimental design and state-of-the-art density estimates, mesopredator abundances were reduced after the restoration of an apex predator, with evidence of resonating positive impacts on lower trophic levels. Specifically, Iberian lynx Lynx pardinus reintroduction was followed by the reduction of the abundance of mesocarnivores (red foxes Vulpes vulpes and Egyptian mongooses Herpestes ichneumon by ca. 80%) and the recovery of small game of high socio-economic value (European rabbits Oryctolagus cuniculus and red-legged partridges Alectoris rufa). The observed mesopredator reduction resulted in an estimated 55,6% less rabbit consumption for the entire carnivore guild. These findings have important implications for the social acceptability of Iberian lynx reintroductions, which crucially depend on the perception of private land owners and managers. Under certain circumstances, restoring apex predators may provide a sustainable and ethically acceptable way to reduce mesopredator abundances. informacion[at]ebd.csic.es: Jiménez et al (2019) Restoring apex predators can reduce mesopredator abundances. Biol Conserv DOI 10.1016/j.biocon.2019.108234


https://www.sciencedirect.com/science/article/pii/S0006320719310092?via%3Dihub