Spatial and temporal genetic variation in small and declining populations of Atlantic salmon
Bibliographic record
Abstract
Atlantic salmon is protected under national and European legislation but most populations are declining. The research investigated population size, habitat quality, population structure and stability over time using Atlantic salmon parr in the River Frome (a chalk stream in Dorset, England) surveyed at 15 sites, in summer and autumn over three consecutive years. The hypotheses were: * Abundance of juvenile Atlantic salmon in a chalk stream is related to habitat quality. * There is significant genetic differentiation between Atlantic salmon within one river, despite small geographic distance between sites and no barriers to migration. * Temporal stability of spatial population structure of Atlantic salmon occurs within a river. Habitat quality, assessed using HABSCORE, varied between sites and over time. Habitat quality was not a predictor of juvenile density but presence of adult brown trout reduced juvenile numbers. DNA for molecular analysis was extracted from fin-clips (removed non-lethally) and genetic variation and distribution of genetic variation was assessed using 5 microsatellites. Relatedness tests indicated that some 0+ parr within a site were closely related. It was inferred that 1+ parr had moved from their natal site, as they could not be assigned to a site of origin. Moderate heterozygosity was detected at each sample site. Low, but significant, genetic differentiation over all sites was detected in summer and autumn for three consecutive years. Isolation by distance was detected at two out of the six sample times, despite small distances between sites. This was strong evidence for structuring within the population. Using a new statistical test, no temporal stability of spatial population structure was detected in the River Frome, but significant temporal stability was detected using published data for Atlantic salmon in a Canadian river.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".