Exposure to UV radiance predicts repeated evolution of concealed black skin in birds

Nicolaï, Michaël P. J.; Shawkey, Matthew D.; Porchetta, Sara; Claus, Ruben; D’Alba, Liliana

doi:10.1038/s41467-020-15894-6

Cited by 40 publications

(43 citation statements)

References 55 publications

(57 reference statements)

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“…However, for brighter feathers maximum skin temperatures were higher than maximum surface temperatures, likely due to deeper light penetration into the plumage [4], backscattering effects [63] and greater transmittance [19]. Interestingly, some sunbird species have black skin, which not only protects them against high ultraviolet irradiation [64] but can further lead to higher heat loads at skin level and more so under higher light transmitting and heat insulating tissues (e.g. as in polar bears [65]).…”

Section: Discussionmentioning

confidence: 99%

Enhanced photothermal absorption in iridescent feathers

Rogalla

Patil

Dhinojwala

et al. 2021

J. R. Soc. Interface.

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The diverse colours of bird feathers are produced by both pigments and nanostructures, and can have substantial thermal consequences. This is because reflectance, transmittance and absorption of differently coloured tissues affect the heat loads acquired from solar radiation. Using reflectance measurements and heating experiments on sunbird museum specimens, we tested the hypothesis that colour and their colour producing mechanisms affect feather surface heating and the heat transferred to skin level. As predicted, we found that surface temperatures were strongly correlated with plumage reflectivity when exposed to a radiative heat source and, likewise, temperatures reached at skin level decreased with increasing reflectivity. Indeed, nanostructured melanin-based iridescent feathers (green, purple, blue) reflected less light and heated more than unstructured melanin-based colours (grey, brown, black), as well as olives, carotenoid-based colours (yellow, orange, red) and non-pigmented whites. We used optical and heat modelling to test if differences in nanostructuring of melanin, or the bulk melanin content itself, better explains the differences between melanin-based feathers. These models showed that the greater melanin content and, to a lesser extent, the shape of the melanosomes explain the greater photothermal absorption in iridescent feathers. Our results suggest that iridescence can increase heat loads, and potentially alter birds' thermal balance.

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Section: Discussionmentioning

confidence: 99%

Enhanced photothermal absorption in iridescent feathers

Rogalla

Patil

Dhinojwala

et al. 2021

J. R. Soc. Interface.

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“…Populations of plants and animals can also genetically adapt to tolerate high UV irradiances. These adaptations are evident in increases in melanin pigment of bird skin with decreasing latitudes [ 164 ], and latitudinal changes in flavonoids of crop plants such as broad bean ( Vicia faba ). In this latter example, a field experiment using UV filters showed that the flavonoid profile of a cultivar native to high elevations in Ecuador and Columbia differed from that of a cultivar from Sweden at low elevation [ 165 ].…”

Section: Terrestrial Ecosystems and Biodiversitymentioning

confidence: 99%

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

Neale

Barnes

Robson

et al. 2021

Photochem Photobiol Sci

131

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This assessment by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) provides the latest scientific update since our most recent comprehensive assessment (Photochemical and Photobiological Sciences, 2019, 18, 595–828). The interactive effects between the stratospheric ozone layer, solar ultraviolet (UV) radiation, and climate change are presented within the framework of the Montreal Protocol and the United Nations Sustainable Development Goals. We address how these global environmental changes affect the atmosphere and air quality; human health; terrestrial and aquatic ecosystems; biogeochemical cycles; and materials used in outdoor construction, solar energy technologies, and fabrics. In many cases, there is a growing influence from changes in seasonality and extreme events due to climate change. Additionally, we assess the transmission and environmental effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, in the context of linkages with solar UV radiation and the Montreal Protocol.

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“…[ 57 ] A very recent study has shown that birds with melanin‐enriched skin live in high radiation regions (closer to equator) and tend to be bald and/or have white feathers, suggesting their black skin is critical for protecting them from UV radiation. [ 58 ]…”

Section: Optical Functions In Naturementioning

confidence: 99%

Bioinspired Melanin‐Based Optically Active Materials

Xiao

Shawkey

Dhinojwala

2020

Advanced Optical Materials

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the properties and functions of melanin, the synthesis of melanin-like nanoparticles, and its versatile applications in catalysis, energy, and biomedical fields. Over the last 5 years, more than 1000 papers on melanin have been published annually, based on data from the Web of Science. Quite a few of these papers have reviewed melanin's chemical structure, physiochemical properties, and biomedical applications. [4-6] However, a critical review focusing on optical functions of melanin is still lacking, despite tremendous emerging work on melaninbased photonic materials. The purpose of this review is to summarize current advances in bioinspired melanin-based optically active materials. Specifically, we will cover inherent optical properties of melanin, and then summarize melanin's optical functions in nature and its optics-related applications. 2. Melanin Structure and Optical Properties Melanin has complex chemical structures that is not yet fully understood, however, it does not hinder the exploration of their optical properties. In this section, we will first discuss classifications of melanin and then summarize unique optical properties of melanin, which will be important for both understanding its biological function in nature and synthetic applications. 2.1. Classification and Structure Conventionally, all black pigments are called melanin. Recently, d'Ischia et al. suggested that any phenolic polymers that have broadband light absorption, antioxidant, and intrinsic free radical character should be characterized as melanin. [5] Exact chemical structures of melanin remain elusive, mainly due to their insolubility in solvents, close binding with other cellular tissues, and an amorphous structure. Here, we do not elaborate on the complexities of melanin's chemical structures, [7] but rather focus on its classification. Melanin can be categorized as either natural or synthetic depending on whether it was synthesized in vivo or in vitro. Both have similar macroscopic properties, but their structures are likely quite different. Natural melanin, including eumelanin, pheomelanin, and neuromelanin, is produced from a series of enzymatic reactions starting from L-tyrosine in biological systems (Figure 1). [1] In cells (commonly melanocytes), the tyrosinase oxidizes L-tyrosine to dopaquinone (DQ). If cysteine concentration in Melanin is a widespread multifunctional biological pigment that has emerged as a promising platform for applications in coating, catalysis, energy, drug delivery, and medical therapy. Melanin is also a compelling material for photonic applications because of its favorable material characteristics, including broadband absorption, high refractive index, tunable fluorescence, and UV blocking capabilities. However, there is not yet a critical review focusing on optical functions of melanin. This review summarizes current advances in bioinspired melanin-based optically active materials, covering melanin's inherent optical properties and functions both in nature and in optics-related applications. It is ...

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Exposure to UV radiance predicts repeated evolution of concealed black skin in birds

Cited by 40 publications

References 55 publications

Enhanced photothermal absorption in iridescent feathers

Enhanced photothermal absorption in iridescent feathers

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

Bioinspired Melanin‐Based Optically Active Materials

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