Cellular Basis of Color Differences in Three Morphs of the Lizard Sceloporus undulatus erythrocheilus

Morrison, Randall L.; Rand, Matthew S.; Frost‐Mason, Sally K.

doi:10.2307/1446903

Cited by 86 publications

(70 citation statements)

References 20 publications

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“…Although these colours are often described as non-iridescent, some authors have noted iridescent features such as changes in colour with angle of observation (e.g. Rohrlich & Porter 1972;Morrison et al 1995). Furthermore, in Sceloporus and Urosaurus lizards, the brick-shaped reflecting platelets found in iridophores are organized in discrete layers, and measured reflectance spectra match those predicted from thin-film models based on the dimensions and refractive indices of those layers (Morrison 1995;Morrison et al 1995Morrison et al , 1996.…”

Section: Taxonomic Distribution Of Iridescence In Animalsmentioning

confidence: 65%

“…Rohrlich & Porter 1972;Morrison et al 1995). Furthermore, in Sceloporus and Urosaurus lizards, the brick-shaped reflecting platelets found in iridophores are organized in discrete layers, and measured reflectance spectra match those predicted from thin-film models based on the dimensions and refractive indices of those layers (Morrison 1995;Morrison et al 1995Morrison et al , 1996. Nevertheless, most structural colours produced by reptiles and amphibians are not strongly iridescent, perhaps as a consequence of irregularities in microstructural organization at larger spatial scales, such as the orientation of iridophores relative to the surface of the skin (Kobelt & Linsenmair 1992).…”

Section: Taxonomic Distribution Of Iridescence In Animalsmentioning

confidence: 99%

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Iridescence: a functional perspective

Doucet

Meadows

2009

J. R. Soc. Interface.

278

289

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In animals, iridescence is generated by the interaction of light with biological tissues that are nanostructured to produce thin films or diffraction gratings. Uniquely among animal visual signals, the study of iridescent coloration contributes to biological and physical sciences by enhancing our understanding of the evolution of communication strategies, and by providing insights into physical optics and inspiring biomimetic technologies useful to humans. Iridescent colours are found in a broad diversity of animal taxa ranging from diminutive marine copepods to terrestrial insects and birds. Iridescent coloration has received a surge of research interest of late, and studies have focused on both characterizing the nanostructures responsible for producing iridescence and identifying the behavioural functions of iridescent colours. In this paper, we begin with a brief description of colour production mechanisms in animals and provide a general overview of the taxonomic distribution of iridescent colours. We then highlight unique properties of iridescent signals and review the proposed functions of iridescent coloration, focusing, in particular, on the ways in which iridescent colours allow animals to communicate with conspecifics and avoid predators. We conclude with a brief overview of noncommunicative functions of iridescence in animals. Despite the vast amount of recent work on animal iridescence, our review reveals that many proposed functions of iridescent coloration remain virtually unexplored, and this area is clearly ripe for future research.

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Section: Taxonomic Distribution Of Iridescence In Animalsmentioning

confidence: 65%

Section: Taxonomic Distribution Of Iridescence In Animalsmentioning

confidence: 99%

Iridescence: a functional perspective

Doucet

Meadows

2009

J. R. Soc. Interface.

278

289

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“…The three distinct facial colour morphs of the fence lizard, Sceloporus undulatus erythrocheilus, differ mainly with respect to xanthophore pigments and iridophore structure (Morrison, Rand & Frost-Mason, 1995). In the orange morph, the xanthophores contain red pteridines (drosopterins) and the iridophores produce a complementary orange reflectance spectrum.…”

Section: Mechanisms Of Colour Production and Colour Change ( 1) mentioning

confidence: 99%

“…This line of reasoning leads to the prediction that iridophore layers with overlying xanthophores should be spectrally flat (or red-shifted), in comparison to iridophores without overlying xanthophores. To our knowledge, no data are currently available to test this prediction, but it could be tested by measuring the reflectance properties of individual iridophores (Fujii et al, 1991 ;Morrison, 1995;Morrison et al, 1995).…”

Section: (C ) Xanthophore Amplificationmentioning

confidence: 99%

Individual colour patches as multicomponent signals

2004

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Colour patches are complex traits, the components of which may evolve independently through a variety of mechanisms. Although usually treated as simple, two-dimensional characters and classified as either structural or pigmentary, in reality colour patches are complicated, three-dimensional structures that often contain multiple pigment types and structural features. The basic dermal chromatophore unit of fishes, reptiles and amphibians consists of three contiguous cell layers. Xanthophores and erythrophores in the outermost layer contain carotenoid and pteridine pigments that absorb short-wave light ; iridophores in the middle layer contain crystalline platelets that reflect light back through the xanthophores ; and melanophores in the basal layer contain melanins that absorb light across the spectrum. Changes in any one component of a chromatophore unit can drastically alter the reflectance spectrum produced, and for any given adaptive outcome (e.g. an increase in visibility), there may be multiple biochemical or cellular routes that evolution could take, allowing for divergent responses by different populations or species to similar selection regimes. All of the mechanisms of signal evolution that previously have been applied to single ornaments (including whole colour patches) could potentially be applied to the individual components of colour patches. To reach a complete understanding of colour patch evolution, however, it may be necessary to take an explicitly multi-trait approach. Here, we review multiple trait evolution theory and the basic mechanisms of colour production in fishes, reptiles and amphibians, and use a combination of computer simulations and empirical examples to show how multiple trait evolution theory can be applied to the components of single colour patches. This integrative perspective on animal colouration opens up a host of new questions and hypotheses. We offer specific, testable functional hypotheses for the most common pigmentary (carotenoid, pteridine and melanin) and structural components of vertebrate colour patches.

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“…The middle layer consists of iridophore cells that produce structural colors through the reflective properties of the cells. Finally, the deepest pigment cell layer produces melanin, and the overall darkness of the body is largely a consequence of the amount of melanin deposited by these melanophores (Bagnara and Hadley 1973;Morrison et al 1995). Unlike mammals and birds, reptile melanophores are known only to produce eumelanin (Bagnara and Hadley 1973), so Mc1r activity might simply affect the amount of melanin produced (rather than switching between the two types of melanin).…”

mentioning

confidence: 99%

Adaptive Reptile Color Variation and the Evolution of the McIr Gene

Rosenblum¹,

Hoekstra²,

Nachman³

2004

Evolution

134

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Abstract. The wealth of information on the genetics of pigmentation and the clear fitness consequences of many pigmentation phenotypes provide an opportunity to study the molecular basis of an ecologically important trait. The melanocortin-1 receptor (Mc1r) is responsible for intraspecific color variation in mammals and birds. Here, we study the molecular evolution of Mc1r and investigate its role in adaptive intraspecific color differences in reptiles. We sequenced the complete Mc1r locus in seven phylogenetically diverse squamate species with melanic or blanched forms associated with different colored substrates or thermal environments. We found that patterns of amino acid substitution across different regions of the receptor are similar to the patterns seen in mammals, suggesting comparable levels of constraint and probably a conserved function for Mc1r in mammals and reptiles. We also found high levels of silent-site heterozygosity in all species, consistent with a high mutation rate or large long-term effective population size. Mc1r polymorphisms were strongly associated with color differences in Holbrookia maculata and Aspidoscelis inornata. In A. inornata, several observations suggest that Mc1r mutations may contribute to differences in color: (1) a strong association is observed between one Mc1r amino acid substitution and dorsal color; (2) no significant population structure was detected among individuals from these populations at the mitochondrial ND4 gene; (3) the distribution of allele frequencies at Mc1r deviates from neutral expectations; and (4) patterns of linkage disequilibrium at Mc1r are consistent with recent selection. This study provides comparative data on a nuclear gene in reptiles and highlights the utility of a candidate-gene approach for understanding the evolution of genes involved in vertebrate adaptation.

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Cellular Basis of Color Differences in Three Morphs of the Lizard Sceloporus undulatus erythrocheilus

Cited by 86 publications

References 20 publications

Iridescence: a functional perspective

Iridescence: a functional perspective

Individual colour patches as multicomponent signals

Adaptive Reptile Color Variation and the Evolution of the McIr Gene

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