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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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Adaptation to high-altitude habitats in the Eastern honey

Adaptation to high-altitude habitats in the Eastern honey

The Eastern honey bee Apis cerana is of central importance for agriculture in Asia. It has adapted to a wide variety of environmental conditions across its native range in southern and eastern Asia, which includes high?altitude regions. Eastern honey bees inhabiting mountains differ morphologically from neighboring lowland populations, and may also exhibit differences in physiology and behavior. The genomes of 60 Eastern honey bees collected from high and low altitudes in Yunnan and Gansu provinces, China, were compared to infer their evolutionary history and to identify candidate genes that may underlie adaptation to high altitude. Using a combination of F_ST?based statistics, long?range haplotype tests, and population branch statistics, several regions of the genome were identified that appear to have been under positive selection. These candidate regions were strongly enriched for coding sequences and had high haplotype homozygosity and increased divergence specifically in highland bee populations, suggesting they have been subjected to recent selection in high altitude habitats. Candidate loci in these genomic regions included genes related to reproduction and feeding behavior in honey bees. Functional investigation of these candidate loci is necessary to fully understand the mechanisms of adaptation to high?altitude habitats in the Eastern honey bee. The results of this research will be very useful to monitor the populations of Asian bees and establish conservation priorities. Pollination services provided by bees are essential for food production throughout the world, but Asian bee populations in China have been declining since the early 20th century due to changes in agricultural practices and the introduction of non-native bees. Therefore, it is important to understand how populations of this species adapt to different environmental conditions such as altitude, as this can help improve conservation efforts and management. informacion[at] Montero-Mendieta et al (2018) The genomic basis of adaptation to high-altitude habitats in the Eastern honey bee (Apis cerana). Mol Ecol DOI 10.1111/mec.14986.