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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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Iberian amphibians occupy higher mountain areas compared to the last century

Iberian amphibians occupy higher mountain areas compared to the last century

Current climate warming has already contributed to local extinctions. Amphibians are one of the most sensitive animal groups to climate change, currently undergoing a global decline. Predictive models for Europe and Iberian Peninsula forecast that the future impact of climate change on amphibians will depend on their capacity to alter their distributions by tracking climate warming. In the present study, the responses of Iberian amphibian species to recent climate change are explored by comparing amphibian distributions between two time periods (1901–1990 vs. 2000–2015). Findings suggest that, although climatic conditions have changed between the two periods, Iberian amphibians have barely shifted their distribution ranges northwards, with the exception of the southernmost species Alytes dickhilleni. However, most Iberian amphibians appear to have moved their elevational limits upwards in mountains. Approximately half of the species showed different occupied niches between the two time periods, suggesting that many Iberian amphibians have not been able to reach all the new location with optimal climatic conditions for them. Furthermore, disappearing cold climatic conditions (e.g. those found at mountain tops) limit the potential distribution of cold-adapted species, including European widespread species with their southern margin in the Iberian Peninsula, and endemic species. The combination of a limited ability to shift their ranges and profound climatic changes could pose a challenge to the long-term persistence of Iberian amphibian populations. informacion[at]ebd.csic.es: Enriquez-Urzelai et al (2019) Are amphibians tracking their climatic niches in response to climate warming? A test with Iberian amphibians. Clim Chang DOI: 10.1007/s10584-019- 02422-9


https://link.springer.com/article/10.1007%2Fs10584-019-02422-9