Why are salmonids pink?
Bibliographic record
Abstract
Pigmented flesh, a trait uniquely present in four of the 10 genera of salmonid fishes, is caused by the ubiquitous capacity of these genera for accumulating dietary carotenoids in muscle tissue. Here we combine life history reasoning with current knowledge of carotenoid metabolism to suggest a possible evolutionary scenario accounting for the emergence and maintenance of this phenotype. We claim that a basal carotenoid metabolism and a hormonally controlled targeted degradation of muscle tissue during maturation were established before the anadromous life style and that these proximal features were concomitantly exploited by natural selection in an ancestral anadromous and nest-making salmonid. Three different selection regimes are suggested to account for available empirical data concerning emergence, as well as maintenance, of the flesh pigmentation trait: a primary one driven by the need for enhanced somatic maintenance accompanying nest making under starving conditions, a secondary one driven by sexual selection, and a tertiary one driven by exposure to a meager carotenoid diet in nonanadromous freshwater populations. Finally, an experimental research program thought to be instrumental for fully resolving this evolutionary puzzle is suggested.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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 source (direct Gemma or distilled Codex), 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".