Balancing selection on size: effects on the incidence of an alternative reproductive tactic
Bibliographic record
Abstract
Question: Does fluctuating natural selection on body size of fish among years (balancing selection) influence the frequency of an alternative male reproductive tactic? Hypothesis: When the surviving juveniles of a cohort are larger because of selection, a higher proportion of the population will develop as mature ‘sneaker’ males than expected in the absence of selection. In the case where selection favours smaller individuals, a lower proportion will develop as mature ‘sneaker’ males. Organisms: Juvenile Atlantic salmon (Salmo salar) from a naturally sustained population in the Ste-Marguerite River, Centre Interuniversitaire de Recherche sur le Saumon Atlantique, Province of Quebec, Canada. Methods: The presence of balancing size-selection was examined by measuring the proportional shift of the mean size and variance of juvenile salmon sampled in the autumn and following spring at multiple sites for each of three annual cohorts. The proportional shift in mean size of individuals over winter was then correlated with the incidence of early male maturity (sneakers) observed at the same sites for each cohort the following fall. Conclusions: Winter mortality decreased the size of surviving fish in one cohort by 7.8% on average, increased size by 2.7% on average in another and had little effect on the third. Proportionally more juvenile males adopted the sneaker tactic when juveniles surviving winter were larger, whereas fewer juvenile males adopted the sneaker tactic when surviving juveniles were smaller. The fluctuating nature of selection on body size indirectly maintains life-cycle divergence through a direct effect on size frequencies within a cohort.
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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 | 0.002 | 0.006 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".