Melanosome diversity and convergence in the evolution of iridescent avian feathers-Implications for paleocolor reconstruction

Nordén, Klara K.; Faber, Jaeike W.; Babarović, Frane; Stubbs, Thomas L.; Selly, Tara; Schiffbauer, James D.; Štefanić, Petra Peharec; Mayr, Gérald; Smithwick, Fiann M.; Vinther, Jakob

doi:10.1111/evo.13641

Cited by 26 publications

(36 citation statements)

References 55 publications

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“…We found a very high intra-multilayer variability for the structural characteristics of melanosomes, as expressed by the high relative standard deviation values reported in table S1. These values are close to previous values reported in the literature for hummingbird multilayers [12], and they likely reflect actual biological variability rather than measurement uncertainty. For example, Greenewalt et al [8] found that layer thickness generally varied between 20-30 % within species.…”

Section: Discussionsupporting

confidence: 88%

“…Consensus phylogeny of the hummingbirds reconstructed using the Maximum Clade Credibility tree from a distribution of 4999 trees downloaded from http://birdtree.org [20]. The red lineages show the 14 species whose structures had been previously studied in the literature [7–10, 12] while blue lineages show species we studied for the first time in this study.…”

Section: Supplementary Figurementioning

confidence: 99%

“…Although all of the 336 species in the family are iridescent [4], the multilayer structures of only 14 hummingbird species (represented on the hummingbird phylogeny in fig. S2) have been studied to this day [7–12]. These fourteen species all had hollow melanin platelets so this type of melanosome was assumed to be present in all hummingbird species [7].…”

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Hummingbird iridescence: an unsuspected structural diversity influences colouration at multiple scales

Gruson

Élias

Djédiat

et al. 2019

Preprint

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10Iridescent colours are colours that change depending on the angle of illumination or observation. They are 11 produced when light is reflected by multilayer structures or diffracted by gratings. While this phenomenon is well 12 understood for simple optical systems, it remains unclear how complex biological structures interact with light 13 to produce iridescence. There are very few comparative studies at interspecific level (often focusing on a single 14 colour patch for each species), resulting in an underestimation of structure diversity. Using an interdisciplinary 15 approach combining physics and biology, we here quantify the colour and structure of 36 hummingbirds species evenly 16 distributed across the phylogeny. We explore at least 2 patches per species, which are assumed to be under different 17 selective regimes. For each patch, we measure structural features (number of layers, layer width, irregularity, spacing, 18 etc.) of the feathers at different scales using both optical and electronic microscopy and we measure colour using a 19 novel approach we developed to encompass the full complexity of iridescence, including its angular dependency. We 20 discover an unsuspected diversity of structures producing iridescence in hummingbirds. We also study the effect of 21 several structural features on the colour of the resulting signal, using both an empirical and modelling approach. Our 22 findings demonstrate the need to take into account multiple patches per species and suggest possible evolutionary 23 pressures causing the evolutionary transitions from one melanosome type to another. 24 Hummingbirds are famous for their bright and shiny colours which change with the illumination or observation 26 angle: a phenomenon known as iridescence. Iridescent colours are produced by the interaction of light with periodic 27 nanometre-scale structures such as multilayers or diffraction gratings and are widespread among many taxa [1]. But few 28 taxa display colours as bright and as saturated as the hummingbirds (Trochilidae family). Most hummingbird species 29 harbour two visually distinct types of iridescent colour patches, as illustrated in fig. S1: directional patches, which are 30 only visible at a very narrow angle range [2] and are often very bright and saturated, and diffuse patches, for which 31 some colour is visible from any angle [2] and that are often not as bright as directional patches. Directional patches are 32 often located on facial or ventral patches and thought to be involved in communication while diffuse patches are often 33 located on dorsal patches and thought to be involved in camouflage [3]. Additionally, although all hummingbird species 34 display some degree of iridescence, striking differences can be noticed between the various species and body patches in 35 terms of brightness (describing how much light is reflected by the object), saturation (describing the colour "purity") 36 and directionality [4]. 37Yet, the structural bases of this intra-individual and interspecific diversity...

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Section: Discussionsupporting

confidence: 88%

Section: Supplementary Figurementioning

confidence: 99%

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Hummingbird iridescence: an unsuspected structural diversity influences colouration at multiple scales

Gruson

Élias

Djédiat

et al. 2019

Preprint

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“…To further understand color evolution in palaeognaths, we examined melanosome morphologies in two extinct lithornithid specimens from the Early Eocene Green River Formation (15) using scanning electron microscopy (SEM). To predict coloration from SEM our image measurements, we used quadratic discriminant function analysis trained with two published datasets on melanosome morphologies in crown birds and nonavian dinosaur taxa (7,16). Some body regions of the extinct lithornithid Calxavis grandei were predicted as glossy black or weakly iridescent (Table 2).…”

Section: Color In An Extinct Palaeognathmentioning

confidence: 99%

Cassowary gloss and a novel form of structural color in birds

Eliason

Clarke

2020

Sci. Adv.

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One of the two lineages of extant birds resulting from its deepest split, Palaeognathae, has been reported not to exhibit structural coloration in feathers, affecting inferences of ancestral coloration mechanisms in extant birds. Structural coloration in facial skin and eggshells has been shown in this lineage, but has not been reported in feathers. We present the first evidence for two distinct mechanisms of structural color in palaeognath feathers. One extinct volant clade, Lithornithidae, shows evidence of elongate melanin-containing organelles uniquely associated with glossy/iridescent color, a structural color mechanism found in fossil outgroups and neognath birds. We also demonstrate a structural basis for the exceptional gloss in extant cassowary feathers. We propose gloss as an intermediate phenotype between matte and iridescent plumage, conferred by a thick and smooth feather rachis. Rachis-based structural color has not been previously investigated. The new data illuminate the relationships between avian melanin-based coloration and feather structure.

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“…In mammals and poultry, melanin is produced in small organelles called melanosomes, which contain all the enzymes necessary for the pigmentation process. Depending on the structure and location of the melanosomes, the colour of the birds plumage may change (Maia et al, 2013;Nordén et al, 2018). Figure 1 shows the structure of the feather follicle during the rest and growth phases.…”

Section: Biochemistry Of Melanin Synthesismentioning

confidence: 99%

Molecular-genetic bases of plumage coloring in chicken

Макарова¹,

Митрофанова²,

Vakhrameev³

et al. 2019

Vestn. VOGiS

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The color of plumage in birds is an important feature, often determining descent to a particular species or breed. It serves as a key factor in the interaction of birds with each other due to their well-developed visual perception of the surrounding world. In poultry including chickens, the color of the plumage can be treated as a genetic marker, useful for identifying breeds, populations and breeding groups with their specific traits. The origin of diverse color plumage is the result of two interrelated physical processes, chemical and optical, due to which pigment and structural colors in the color are formed. The pigment melanin, which is presented in two forms, eumelanin and pheomelanin, is widely spread in birds. The basis for the formation of melanin is the aromatic amino acid tyrosine. The process of melano-genesis involves many loci, part of the complex expression of plumage color genes. In birds, the solid black color locus encodes the melanocortin 1 receptor (MC1R), mutations in which lead to a change in receptor activation and form different variants of the E locus. Using the GWAS analysis, possible genes affecting the formation of color in chickens were detected. The biosynthesis and types of melanin are affected by the activity of the enzyme tyrosine, and mutations in the tyrosinase gene (TYR) cause albinism in different species. The formation mechanism of brown, silver, gold, lavender and a number of other shades is determined by the influence on the work of the MC1R genes and TYR specific modifier genes. Thus, locus I currently associated with the PMEL17 gene inhibits the expression of eumelanin, and the MLPH gene affects tyrosinase function. Research on the mechanisms of formation of the secondary coloring of plumage in chickens is being actively conducted nowadays. The formation of a marble feather pattern is associated with the mutation of the endothelin B2 receptor (EDNRB2), in the coding part of the gene of which a polymorphism is found associated with the mo locus. The molecular base that causes the feather banding (locus B and autosomal recessive banding) is identified. Today, only some genes that determine the color of the plumage of chickens are studied and described. Different genes can produce similar plumage patterns, and different phenotypes can be determined by the polymorphism of a single gene. Using molecular methods, you can more accurately identify these differences. This overview shows the nature of melanin coloration in birds using the example of chickens of various breeds and also attempts to systematize knowledge about the molecular-genetic mechanisms of the appearance of various types of coloration.

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Melanosome diversity and convergence in the evolution of iridescent avian feathers-Implications for paleocolor reconstruction

Cited by 26 publications

References 55 publications

Hummingbird iridescence: an unsuspected structural diversity influences colouration at multiple scales

Hummingbird iridescence: an unsuspected structural diversity influences colouration at multiple scales

Cassowary gloss and a novel form of structural color in birds

Molecular-genetic bases of plumage coloring in chicken

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