A millennium of stasis in avian ornamentation? Implications for sexual selection theory
Bibliographic record
Abstract
Sexual selection is widely accepted as an explanation for the evolution of ornamental traits in animals. Theory predicts that ornament evolution via sexual selection is triggered when a population is moved from an equilibrium state by changes in environmental conditions or population parameters and that once initiated, the rate of change can be rapid in comparison to change induced by natural selection. To assess these ideas, we considered whether there are examples of substantive changes to ornamental traits in any species of bird over recent human history. We proposed and tested a new means to assess contemporary evolution in the ornamental traits in birds, covering a period of more than a thousand years before present. We predicted that cases of rapid change in avian ornaments would be captured in the pictorial record across the centuries for which bird plumage has been documented. We found no substantial change in the ornamental traits of any species of bird, and we found few instances of even small changes in the ornamentation of bird species as depicted in the historical record. Our study is the first to systematically evaluate changes in ornamental traits within extant species on a time scale of centuries, and our findings have important implications for the mechanisms that generate the diversity of ornaments in birds.
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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 | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.006 | 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".