No evidence for melatonin-linked immunoenhancement over the annual cycle of an avian species
Bibliographic record
Abstract
The winter immunoenhancement hypothesis associates long nights and increased exposure to melatonin with enhanced immune function in winter when resource availability is low and the chances of becoming ill are high. Thus, increased exposure to melatonin in the winter could be adaptive for species facing difficult winter conditions. This idea has found some support in studies of resident mammals. In birds, the link between day length and melatonin over the annual cycle is weaker, and contributions of melatonin to seasonal timing are unclear. Furthermore, many species, especially migrants, do not experience the most difficult conditions of their annual cycle in winter. In this study, we tested whether the winter immunoenhancement hypothesis holds in an avian species, the red knot Calidris canutus. We found that melatonin duration and amplitude varied significantly over the annual cycle with the highest values occurring in winter. However, peaks did not correspond to the winter solstice or with annual variation in immune function. Our findings do not support the winter immunoenhancement hypothesis in knots and question whether the idea that immune function should be bolstered in winter can be generalized to systems where winter is not the most difficult time of the year.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.002 | 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 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".