CAPTIVE BREEDING REDUCES BRAIN VOLUME IN WATERFOWL (ANSERIFORMES)
Bibliographic record
Abstract
Abstract Brain-size reduction in domesticated forms of mammals in comparison to their wild ancestors is well documented in numerous species. Although it does not involve intentional artificial selection for traits such as meat production, captive breeding also causes a reduction in brain size in some mammalian species. In birds, domestication results in a reduction in brain size as well, but whether captive breeding causes a similar effect is unknown. Given the increasing number of avian captive breeding programs, it is important to assess whether captive breeding affects the behavior and morphology of a species. Here we investigated whether relative and absolute brain volume differs between wild and captive-bred stocks of 21 species of waterfowl (Anseriformes). Absolute brain volume of captive-bred specimens was lower than in wild specimens for most (16 of 21) of the species examined, and the decrease varied from 1% to 33% (mean: 4.7%). Similarly, all but one species showed relative brain-volume decrease that varied between 2% and 30% (mean: 7.7%). Overall, these reductions in absolute and relative brain volume are smaller than that caused by domestication in ducks (Anas platyrhynchos) and geese (A. anser) but are larger than the decreases observed in captive-bred mammals. Thus, captive breeding appears to result in a decrease in both absolute and relative brain volumes in waterfowl. How this reduction reflects changes in behavior or brain composition is unknown, but it may nevertheless have important implications for the successful reintroduction of captive-bred individuals in the wild.
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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 | 0.000 |
| 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) | 0.001 | 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 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".