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Link to original content: https://pubmed.ncbi.nlm.nih.gov/32415098
Exposure to UV radiance predicts repeated evolution of concealed black skin in birds - PubMed Skip to main page content
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. 2020 May 15;11(1):2414.
doi: 10.1038/s41467-020-15894-6.

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

Michaël P J Nicolaï  1   2 , Matthew D Shawkey  3 , Sara Porchetta  4   5 , Ruben Claus  3 , Liliana D'Alba  3
Affiliations

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

Michaël P J Nicolaï et al. Nat Commun. .

Abstract

Plumage is among the most well-studied components of integumentary colouration. However, plumage conceals most skin in birds, and as a result the presence, evolution and function of skin colour remains unexplored. Here we show, using a database of 2259 species encompassing >99% of bird genera, that melanin-rich, black skin is found in a small but sizeable percentage (~5%) of birds, and that it evolved over 100 times. The spatial distribution of black skin follows Gloger's rule, which states that pigmentation of endothermic animals increases towards the equator. Furthermore, most black-skinned birds inhabit high irradiation regions, and tend to be bald and/or have white feathers. Thus, taken together, our results suggest that melanin-rich, black skin helps to protect birds against ultraviolet irradiation. More generally, our results illustrate that feathered skin colour varies taxonomically, ontogenetically and temporally, providing an additional dimension for avian colour research.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Differences in skin colour of (a) Morus bassanus (black) and (b) Garrulus glandarius (red) are due to differences in melanin concentration as seen under light microscopy for (c, e) M. bassanus and (d, f) for G. glandarius.
Scale bars represent 50 μm (c, d), 30 µm (e, f) and 1 µm (g). e stands for epidermis, m for melanin. While melanin is present in both tissues, concentrations appear much higher in black skin. g Detail of a melanophore containing individual melanosomes (few examples indicated by an m) from M. bassanus (scale bar 1 µm).
Fig. 2
Fig. 2. Ancestral state estimation for black skin of the heads of male birds.
Branches of the phylogenetic tree are black when the reconstructed skin colour was black, and red when this was non-black. Black bars in the first circle represent species that are bald, while black bars in second circle represent species that have white feathers. All photographs were edited such that the background was removed. Photographs were taken by U.S. Fish & Wildlife Service (Telespiza cantans), Kenvanportbc (Amblyramphus holosericeus) and Adrian Pingstone (Coscoroba coscoroba) in the public domain, by Hector Bottai (Hylexetastes perrotii, Hapalocrex flaviventer) and Charles J Sharp (Ardea alba) under CC BY-SA 4.0 (https://creativecommons.org/licences/by-sa/4.0/), by Thai National Parks (Hemixos flavala), birdphotos.com (Bugeranus carunculatus) and Dubi Shapiro (Neodrepanis hypoxantha) under CC BY SA 3.0 (https://creativecommons.org/licences/by-sa/4.0/), by Flickr-users under CC BY 2.0 Bernard DUPONT (Lybius torquatus), Lip Kee (Camptostoma obsoletum), Francesco Veronesi (Hedydipna platura), Ben Tavener (Procnias nudicollis), Michael Andersen (Picathartes gymnocephalus), Frank Vassen (Falculea palliata), jquental (Anopetia gounellei), Alastair Rae (Malcorus pectoralis), Brian Jelonek (Tauraco leucolophus) and Alan D. Wilson (Auriparus flaviceps) under CC BY SA 2.5 (https://creativecommons.org/licences/by-sa/2.5/), by wiki-users Ariefrahman (Macrocephalon maleo), Mdk572 (Sugomel niger), Peripitus (Hylacola cautus), Prateik Kulkarni (Ianthocincla albogularis), Dasari. Vijay (Hydrophasianus chirurgus) under CC BY SA 4.0 (https://creativecommons.org/licences/by-sa/4.0/), Doug Janson (Urocolius macrourus), Helenabella (Cladorhynchus leucocephalus), Mdf (Coragyps atratus), Tragopan (Phoenicopterus chilensis), DickDaniels (Argusianus argus), Serhanoksay (Cicinnurus respublica) under CC BY SA 3.0 (https://creativecommons.org/licences/by-sa/3.0/) and scorpious18 (Pithecophaga jefferyi), jomilo75 (Pagophila eburnean), and Jcwf (Leucopsar rothschildi) under CC BY SA 2.0 (https://creativecommons.org/licences/by/2.0/).
Fig. 3
Fig. 3. Black skin in function of UV radiance and feather colour.
a Black skin probability in function of relative UV radiance (UV radiance/max UV radiance) for all birds, non-passerines and passerines (data shown for female dataset only). Observed proportion of black skin relative to non-black skin in function of feather colour for all birds (b), non-passerines (c) and passerines (d) (Supplementary Table 8).
Fig. 4
Fig. 4. Probability of black skin occurrence estimated by MAXENT using solar radiation (kJm-2day-1), average precipitation (mm), and average maximum temperature (°C) as predictor values in passerines (A) and non-passerines (B).
Additional panes reflect the difference of the predicted black skin probabilities in relation to UV radiation in passerines (c) and non-passerines (d); The difference of predicted probabilities and relative maximum temperature (maximum temperature/maximal maximum temperature value) in passerines (e) and non-passerines (f); The difference of predicted probabilities and relative precipitation (precipitation/maximal precipitation value) in passerines (g) and non-passerines (h); The relative bird biodiversity (bird biodiversity/maximal bird biodiversity) (i) and the distribution of black skin colour in humans (j) (Adapted from Chaplin). The darkness gradients in a, b and j indicate the probability of black skin being present: high probability regions are dark, low probability regions are white. In b–d values near 0 (white) indicate a good fit between predictor value and black skin probability while non-zero values indicate increasing tendencies to a mismatch between predictor and predictor indicating that another variable contributes more to the black skin prediction model. All climatic variables were yearly averaged over a span of 30 years.
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References

    1. Darwin, C. R. The Descent of Man, and Selection in Relation to Sex. (John Murray, 1871).
    1. Newton, I. Opticks. (William Innys at the West-End of St. Paul’s, London, 1730).
    1. Dale J, Dey CJ, Delhey K, Kempenaers B, Valcu M. The effects of life history and sexual selection on male and female plumage colouration. Nature. 2015;527:367–370. doi: 10.1038/nature15509. - DOI - PubMed
    1. McCoy DE, Feo T, Harvey TA, Prum RO. Structural absorption by barbule microstructures of super black bird of paradise feathers. Nat. Commun. 2018;9:1. doi: 10.1038/s41467-017-02088-w. - DOI - PMC - PubMed
    1. Auber L. The distribution of structural colours and unusual pigments in the class Aves. Ibis. 1957;99:463–476. doi: 10.1111/j.1474-919X.1957.tb01960.x. - DOI

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