Structural Plumage Coloration, Male Body Size, and Condition in the Blue-Black Grassquit
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".