scholarly journals Blue reflectance in tarantulas is evolutionarily conserved despite nanostructural diversity

2015 ◽  
Vol 1 (10) ◽  
pp. e1500709 ◽  
Author(s):  
Bor-Kai Hsiung ◽  
Dimitri D. Deheyn ◽  
Matthew D. Shawkey ◽  
Todd A. Blackledge
Keyword(s):  
Sexual Selection ◽  
Phylogenetic Reconstruction ◽  
Blue Color ◽  
Structural Mechanism ◽  
Multilayer Nanostructures ◽  
Structural Colors ◽  
Color Differences ◽  
Structural Mechanisms ◽  
20 Nm ◽  
Blue Coloration

Slight shifts in arrangement within biological photonic nanostructures can produce large color differences, and sexual selection often leads to high color diversity in clades with structural colors. We use phylogenetic reconstruction, electron microscopy, spectrophotometry, and optical modeling to show an opposing pattern of nanostructural diversification accompanied by unusual conservation of blue color in tarantulas (Araneae: Theraphosidae). In contrast to other clades, blue coloration in phylogenetically distant tarantulas peaks within a narrow 20-nm region around 450 nm. Both quasi-ordered and multilayer nanostructures found in different tarantulas produce this blue color. Thus, even within monophyletic lineages, tarantulas have evolved strikingly similar blue coloration through divergent mechanisms. The poor color perception and lack of conspicuous display during courtship of tarantulas argue that these colors are not sexually selected. Therefore, our data contrast with sexual selection that typically produces a diverse array of colors with a single structural mechanism by showing that natural selection on structural color in tarantulas resulted in convergence on similar color through diverse structural mechanisms.

scholarly journals The dynamics of faculty hiring networks

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Eun Lee ◽  
Aaron Clauset ◽  
Daniel B. Larremore
Keyword(s):  
Network Models ◽  
Structural Mechanism ◽  
Faculty Hiring ◽  
Network Characteristics ◽  
Institutional Prestige ◽  
Structural Mechanisms ◽  
Global And Local ◽  
Global Placement ◽  
New Hire

AbstractFaculty hiring networks—who hires whose graduates as faculty—exhibit steep hierarchies, which can reinforce both social and epistemic inequalities in academia. Understanding the mechanisms driving these patterns would inform efforts to diversify the academy and shed new light on the role of hiring in shaping which scientific discoveries are made. Here, we investigate the degree to which structural mechanisms can explain hierarchy and other network characteristics observed in empirical faculty hiring networks. We study a family of adaptive rewiring network models, which reinforce institutional prestige within the hierarchy in five distinct ways. Each mechanism determines the probability that a new hire comes from a particular institution according to that institution’s prestige score, which is inferred from the hiring network’s existing structure. We find that structural inequalities and centrality patterns in real hiring networks are best reproduced by a mechanism of global placement power, in which a new hire is drawn from a particular institution in proportion to the number of previously drawn hires anywhere. On the other hand, network measures of biased visibility are better recapitulated by a mechanism of local placement power, in which a new hire is drawn from a particular institution in proportion to the number of its previous hires already present at the hiring institution. These contrasting results suggest that the underlying structural mechanism reinforcing hierarchies in faculty hiring networks is a mixture of global and local preference for institutional prestige. Under these dynamics, we show that each institution’s position in the hierarchy is remarkably stable, due to a dynamic competition that overwhelmingly favors more prestigious institutions. These results highlight the reinforcing effects of a prestige-based faculty hiring system, and the importance of understanding its ramifications on diversity and innovation in academia.

scholarly journals The weaker sex: Male lingcod (Ophiodon elongatus) with blue color polymorphism are more burdened by parasites than are other sex–color combinations

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261202
Author(s):  
Chelsea L. Wood ◽  
Katie L. Leslie ◽  
Alanna Greene ◽  
Laurel S. Lam ◽  
Bonnie Basnett ◽  
...  
Keyword(s):  
Parasite Burden ◽  
Liver Weight ◽  
Color Polymorphism ◽  
Future Research ◽  
Hepatosomatic Index ◽  
Color Morph ◽  
Blue Color ◽  
Ophiodon Elongatus ◽  
Color Combinations ◽  
Blue Coloration

The unusual blue color polymorphism of lingcod (Ophiodon elongatus) is the subject of much speculation but little empirical research; ~20% of lingcod individuals exhibit this striking blue color morph, which is discrete from and found within the same populations as the more common brown morph. In other species, color polymorphisms are intimately linked with host–parasite interactions, which led us to ask whether blue coloration in lingcod might be associated with parasitism, either as cause or effect. To test how color and parasitism are related in this host species, we performed parasitological dissection of 89 lingcod individuals collected across more than 26 degrees of latitude from Alaska, Washington, and California, USA. We found that male lingcod carried 1.89 times more parasites if they were blue than if they were brown, whereas there was no difference in parasite burden between blue and brown female lingcod. Blue individuals of both sexes had lower hepatosomatic index (i.e., relative liver weight) values than did brown individuals, indicating that blueness is associated with poor body condition. The immune systems of male vertebrates are typically less effective than those of females, due to the immunocompromising properties of male sex hormones; this might explain why blueness is associated with elevated parasite burdens in males but not in females. What remains to be determined is whether parasites induce physiological damage that produces blueness or if both blue coloration and parasite burden are driven by some unmeasured variable, such as starvation. Although our study cannot discriminate between these possibilities, our data suggest that the immune system could be involved in the blue color polymorphism–an exciting jumping-off point for future research to definitively identify the cause of lingcod blueness and a hint that immunocompetence and parasitism may play a role in lingcod population dynamics.

Strucutural Color Bio-Engineering by Replicating Morpho Wings

2011 ◽  
Vol 391-392 ◽  
pp. 409-417 ◽  
Author(s):  
Yu Ping Liu ◽  
Lei Huang ◽  
Wang Zhou Shi
Keyword(s):  
Low Temperature ◽  
Atomic Layer ◽  
Hybrid Structures ◽  
Blue Color ◽  
Inorganic Hybrid ◽  
Structural Colors ◽  
Layer Deposition ◽  
Simulation Results ◽  
Controlled Deposition ◽  
Bio Engineering

Cover scales and ground scales are found to be responsible for the greenish blue color of Morpho menelaus. From simulation predictions, different colors can be engineered by controlled thickness coatings on surface of scales. By replicating the morphologies of scales with low-temperature atomic layer deposition (ALD) methods, tunable colors are achieved successful by regulations of deposition cycles of Al2O3in the organic-inorganic hybrid structures. After removal of original structures by means of high temperatures, inverted nanostructures exhibiting colors sealed by Al2O3shell are fabricated. Simulation results of the hybrid and inverted structures are in accordance with experimental results well. The predictable spectra and the executable precisely controlled deposition by ALD provide us the potential of designing and constructing diversified structural colors.

scholarly journals Instrumental Factors Influencing Absorption Measurements for Fluid Food Color Determination

2004 ◽  
Vol 87 (3) ◽  
pp. 632-638 ◽  
Author(s):  
Cristina Montes ◽  
Joaquín Campos ◽  
Alicia Pons ◽  
Francisco J Heredia
Keyword(s):  
Grape Juice ◽  
Natural Pigment ◽  
Color Changes ◽  
Color Differences ◽  
Tristimulus Values ◽  
Actual Color ◽  
20 Nm ◽  
Spectral Weighting ◽  
Different Sources ◽  
Absorption Measurements

Abstract The differences in color coordinates obtained from the use of different spectral features in the calculation are studied. Seven groups of food (olive oil, vanilla milkshake, brandy, honey, grape juice, vinegar, and orange juice) and an anthocyanin petunidin solution (natural pigment present in several vegetables) with different pH values were selected. Tristimulus values were calculated by considering the different sources of errors (truncation, abridgement, or different bandwidths). Results obtained were corrected by using the methods recommended (see References). These methods of abridgment work well in general, although in some circumstances (20 nm bandwidth or larger), specific spectral weighting functions have to be used to obtain a negligible error. Therefore, it is interesting to know how much difference can be expected from those factors in order to avoid confusion between color differences attributable to instruments and those attributable to actual color changes.

scholarly journals The evolution of coloration and opsins in tarantulas

2020 ◽  
Vol 287 (1935) ◽  
pp. 20201688
Author(s):  
Saoirse Foley ◽  
Vinodkumar Saranathan ◽  
William H. Piel
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Mate Choice ◽  
Colour Vision ◽  
Mate Searching ◽  
Predation Avoidance ◽  
Opsin Genes ◽  
Ancestral States ◽  
Green Coloration ◽  
Blue Coloration

Tarantulas paradoxically exhibit a diverse palette of vivid coloration despite their crepuscular to nocturnal habits. The evolutionary origin and maintenance of these colours remains mysterious. In this study, we reconstructed the ancestral states of both blue and green coloration in tarantula setae, and tested how these colours correlate with presence of stridulation, urtication and arboreality. Green coloration has probably evolved at least eight times, and blue coloration is probably an ancestral condition that appears to be lost more frequently than gained. While our results indicate that neither colour correlates with the presence of stridulation or urtication, the evolution of green coloration appears to depend upon the presence of arboreality, suggesting that it ptobably originated for and functions in crypsis through substrate matching among leaves. We also constructed a network of opsin homologues across tarantula transcriptomes. Despite their crepuscular tendencies, tarantulas express a considerable diversity of opsin genes—a finding that contradicts current consensus that tarantulas have poor colour vision on the basis of low opsin diversity. Overall, our findings raise the possibility that blue coloration could have ultimately evolved via sexual selection and perhaps proximately be used in mate choice or predation avoidance due to possible sex differences in mate-searching.

scholarly journals Objective Assessment of Sexual Plumage Dichromatism in the Picui Dove

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 248-254
Author(s):  
Bettina Mahler ◽  
Bart Kempenaers
Keyword(s):  
Sexual Selection ◽  
Objective Assessment ◽  
Spectral Shape ◽  
Sexual Dichromatism ◽  
Sexually Dimorphic ◽  
Near Ultraviolet ◽  
Body Regions ◽  
Color Differences ◽  
Objective Determination

Abstract The Picui Dove (Columbina picui) has been considered sexually monochromatic, with females slightly duller than males. This assessment has been based on colors perceived by the human eye. However, birds possess an additional, near-ultraviolet photoreceptor and thus are sensitive to wavelengths humans are not. Measurements of reflectance using spectroradiometry permit an objective determination of the coloration of the birds' plumage and of color differences between the sexes. We here show that the plumage coloration of the Picui Dove is clearly sexually dimorphic. Males were overall brighter than females, and several body regions showed a significant sex difference in spectral shape. These results imply that studies of sexual selection in this and related species should measure sexual dichromatism objectively, and should not rely on human color perception. Determinación Objetiva del Dicromatismo Sexual del Plumaje en Columbina picui Resumen. La especie Columbina picui ha sido considerada sexualmente monocromática, siendo las hembras levemente más opacas que los machos. Esta conclusión ha sido basada en la percepción humana del color. Sin embargo, las aves poseen un fotorreceptor adicional en el ultravioleta cercano y son, por lo tanto, sensibles a longitudes de onda que los humanos no perciben. La medición de la reflectancia por medio de la técnica de espectrofotometría permite una determinación objetiva del color del plumaje y de las diferencias de color entre los sexos. En este estudio mostramos que C. picui es claramente sexualmente dicromática, siendo los machos más brillantes que las hembras y presentando en algunas regiones del cuerpo diferencias en el espectro de las longitudes de onda reflejadas. Estos resultados demuestran que la determinación de dicromatismo sexual no debería basarse en la percepción humana y tiene, además, implicancias para los estudios de selección sexual en esta especie y especies relacionadas.

scholarly journals Resolving color differences of comet 41P/Tuttle-Giacobini-Kresák

2020 ◽  
Vol 642 ◽  
pp. L5
Author(s):  
Igor Luk’yanyk ◽  
Evgenij Zubko ◽  
Gorden Videen ◽  
Oleksandra Ivanova ◽  
Anton Kochergin
Keyword(s):  
Wavelength Range ◽  
Mineral Dust ◽  
Strong Dependence ◽  
Additional Constraint ◽  
Blue Color ◽  
Cometary Dust ◽  
Particle Absorption ◽  
Red Color ◽  
Color Differences ◽  
Measurement Campaigns

Three different measurement campaigns have resulted in three drastically different sets of color measurements of Comet 41P/Tuttle-Giacobini-Kresák, ranging from a strongly red to a strongly blue color. Although the color slope is normalized to the wavelength range between the filters used, this only serves to partially normalize the resulting color, as the reflectance of cometary dust has a very strong dependence on particle absorption, which may change significantly over the wavelength range of measurement. We demonstrate that the different measurements are physical and are consistent with real materials; for example, we are able to reproduce the color measured during one epoch in which both strong blue and red color slopes were measured almost simultaneously in different filter sets with the mineral dust pyroxene. Such measurements with different filter sets serve as an additional constraint in modeling dust properties.

scholarly journals Structural mechanism for bi-directional actin crosslinking by T-plastin

2021 ◽  
Author(s):  
Lin Mei ◽  
Matthew J Reynolds ◽  
Damien Garbett ◽  
Rui Gong ◽  
Tobias Meyer ◽  
...  
Keyword(s):  
Bone Diseases ◽  
Biological Data ◽  
Structural Elements ◽  
Structural Mechanism ◽  
Actin Networks ◽  
Network Geometry ◽  
Cytoskeletal Network ◽  
Mixed Polarity ◽  
Scale Network ◽  
Structural Mechanisms

To fulfill the cytoskeleton's diverse functions in cell mechanics and motility, actin networks with specialized architectures are built by crosslinking proteins, which bridge filaments to control micron-scale network geometry through nanoscale binding interactions via poorly defined structural mechanisms. Here, we introduce a machine-learning enabled cryo-EM pipeline for visualizing active crosslinkers, which we use to analyze human T-plastin, a member of the evolutionarily ancient plastin/fimbrin family of tandem calponin-homology domain (CHD) proteins. We define a sequential bundling mechanism which enables T-plastin to bridge filaments in both parallel and anti-parallel orientations. Our structural, biochemical, and cell biological data highlight inter-CHD linkers as key structural elements underlying flexible but stable crosslinking which are likely to be disrupted by mutations causing hereditary bone diseases. Beyond revealing how plastins are evolutionary optimized to crosslink dense actin networks with mixed polarity, our cryo-EM workflow will broadly enable analysis of the structural mechanisms underlying cytoskeletal network construction.

scholarly journals Wide gamut, angle-insensitive structural colors based on deep-subwavelength bilayer media

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3385-3392 ◽  
Author(s):  
Hui Pan ◽  
Zhengji Wen ◽  
Zhihong Tang ◽  
Gangyi Xu ◽  
Xiaohang Pan ◽  
...  
Keyword(s):  
Color Space ◽  
Metallic Substrate ◽  
Structural Color ◽  
Blue Color ◽  
Planar Bilayer ◽  
Structural Colors ◽  
Reflected Wave ◽  
Fabry Perot ◽  
New Type ◽  
P Type

AbstractWide gamut and angle-insensitive structural colors are highly desirable for many applications. Herein, a new type of lithography-free, planar bilayer nanostructures for generating structural colors is presented, which is basically composed of a deep-subwavelength, highly absorbing dielectric layer on an opaque metallic substrate. Experimental results show that a galaxy of brilliant structural colors can be generated by our structures, and which can cover ∼50% of the standard red–green–blue color space by adjusting the nanostructure dimensions. The color appearances are robust with respect to the angle of vision. Theoretical partial reflected wave analyses reveal that the structural color effect is attributed to the strong optical asymmetric Fabry–Perot-type (F–P-type) thin-film resonance interference. The versatility of the structural color properties as well as the simplicity of their fabrication processes make this bilayer structures very promising for various applications, such as security marking, information encryption, and color display, etc.

scholarly journals Structural Plumage Coloration, Male Body Size, and Condition in the Blue-Black Grassquit

The Condor ◽  
2002 ◽  
Vol 104 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Stéphanie M. Doucet
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Plumage Coloration ◽  
Positive Trend ◽  
Male Body ◽  
Male Body Size ◽  
Structural Colors ◽  
Body Regions ◽  
Male Condition ◽  
Color Score

Abstract In birds, the colors ultraviolet, blue, and green originate from feather microstructure rather than pigmentation. Structural plumage coloration may be maintained by sexual selection, yet there exists only limited evidence that structural colors can honestly signal individual quality. In this study, I found considerable individual variation in the blue-black to ultraviolet coloration of the wing coverts and rump of male Blue-black Grassquits (Volatinia jacarina), thereby revealing the potential for sexual selection on structural plumage coloration in this species. I used a principal components analysis (PCA) of four color characteristics to combine reflectance data into a single color score. Birds with high color scores have brighter, more intensely colored, and more saturated blue-black feathers. There was a significant positive relationship between color scores for both body regions and male condition. There was also a positive trend between the color score of the rump region and male body size. These results support recent findings that structural plumage coloration is condition-dependent, and this type of coloration may be an honest signal of male quality in the Blue-black Grassquit. Coloración Estructural del Plumaje, Tamaño Corporal y Condición Física en Machos de Volatinia jacarina Resumen. En las aves, los colores ultravioleta, azul y verde están dados por la microestructura de las plumas y no por la pigmentación. La coloración estructural del plumaje puede ser mantenida por selección sexual, aunque existe poca evidencia que indique que los colores estructurales son un indicador confiable de la calidad de un individuo. En este estudio encontré variación individual considerable en la coloración negro-azulada a ultravioleta de las cobertoras alares y la rabadilla de machos de Volatinia jacarina, revelando que la coloración estructural del plumaje en esta especie podría estar sujeta a selección sexual. Utilicé un análisis de componentes principales (PCA) de cuatro características de color para combinar datos de reflectancia en un solo valor de color. Las aves con altos valores de color tienen plumas más brillantes e intensamente coloreadas y más saturadas de color negro-azulado. Existió una relación positiva significativa entre los valores de color para ambas regiones del cuerpo y la condición física de los machos. También hubo una tendencia positiva entre el valor del color de la región de la rabadilla y el tamaño corporal de los machos. Estos resultados apoyan descubrimientos recientes que demuestran que la coloración estructural del plumaje depende de la condición física, y que este tipo de coloración puede ser una señal confiable de la calidad de los machos de V. jacarina.

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