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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] Neves et al (2020) Impairment of mixed melanin-based pigmentation in parrots. J Experim Biol. DOI 10.1242/jeb.225912
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Vertebrate road-kill patterns in Mediterranean habitats: who, when and where.

Vertebrate road-kill patterns in Mediterranean habitats: who, when and where.

Road-kill is the most recognized impact of traffic and an important threat for biodiversity. Nevertheless, most research on this topic deals with particular species or with road features, describing proximate correlates and rarely making inference on the mechanisms. Here it is provided a more general approximation by describing life-history, temporal and spatial factors affecting vertebrate road-kills in Mediterranean landscapes, a biodiversity hotspot with little studied road impacts. During one year authors recorded the casualties found on paved roads within Doñana Natural Park. More than 2300 road-kills belonging to 66 species (32% of the study area checklist) were found, with abundant ectotherm species more likely to be road-killed. The temporal and spatial factors affecting the road-kill patterns of different taxonomic and functional groups were also investigated. The phenology of the species was the main factor affecting road-kill temporal patterns for lizards, all birds and small mammals. Additionally, rainfall events were associated with the road-kill peaks of wintering birds, whereas high temperatures were related to the increase of road-killed snakes and the decrease of road-killed amphibians. Amphibians, snakes, lizards and small passerines were mainly road-killed according with their spatial abundance. Mitigation measures such as wildlife road-crossing structures showed contradictory effectiveness for small vertebrates due to the lack of adequate drift fences. Authors suggest prioritizing the mitigation measures which can permanently decrease the risk of been road-killed for ectotherm species, such as specific road-crossing structures with effective drift fences on road-kill hotspots. Concurrently, group-specific temporal mitigation measures should be applied during the road-kill seasonal peaks. The present work provides recommendations to decrease road-kill impacts in Mediterranean environments, but simultaneously tries to contribute to a more general development of road ecology research, suggesting several useful guidelines to perform road-kill studies. informacion[at] D'Amico et al (2015) Vertebrate road-kill patterns in Mediterranean habitats: Who, when and where. Biol Conserv 191: 234–242 DOI: 10.1016/j.biocon.2015.06.010