Rhodoxanthin as a characteristic keto-carotenoid of manakins (Pipridae)
Bibliographic record
Abstract
Manakins are small suboscine passerines renowned for elaborate courtship displays and pronounced sexual dichromatism. We extracted and identified the carotenoid pigments found in the bright yellow to red feathers of 15 Neotropical manakin species. Rhodoxanthin (4′,5′-didehydro-4,5′-retro-β,β-carotene-3,3′-dione) of a deep red hue was widely found in the plumages of these birds. The 4-keto-carotenoids typically found in red plumages (α-doradexanthin, astaxanthin, canthaxanthin, etc.) were found in only the Flame-crested Manakin (Heterocercus linteatus) and the Red-headed Manakin (Pipra rubrocapilla). Rhodoxanthin was recently identified in the Pin-tailed Manakin (Ilicura militaris). Hudon et al. (2007) suggested that the Pin-tailed Manakin produces rhodoxanthin endogenously from dietary carotenoids, and this suggestion now finds some support in the pigment's wide and specific distribution in manakins. It is possible that this capacity arose in a common ancestor of manakins and cotingas, given that rhodoxanthin also occurs in the feathers of red cotingas (Phoenicircus spp.). Feathers with rhodoxanthin absorbed longer wavelengths of light than those with 4-ketocarotenoids, but not in Pipra, which has species with one or the other type of keto-carotenoids. We found that feathers with rhodoxanthin also contained ε,ε-caroten-3(3′)-ones (e.g., canary-xanthophyll B and the recently described piprixanthin), which are believed to be intermediates along the rhodoxanthin pathway. Manakins thus have the capability to produce a wide range of carotenoid pigments and bright yellow to red colors, on which natural and sexual selection may act.
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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".