Divergence in thyroid hormone concentrations between juveniles of marine and stream ecotypes of the threespine stickleback (Gasterosteus aculeatus)
Bibliographic record
Abstract
Background: Hormones regulate the expression of multiple phenotypic traits. Therefore, divergence in hormone concentrations may lead to evolutionary changes in the coordinated physiological and behavioural traits that comprise an organism’s integrated phenotype. Adults of marine ecotypes of threespine stickleback (Gasterosteus aculeatus) have higher concentrations of the thyroid hormone thyroxine (T4) than adults of stream-resident ecotypes (Kitano et al., 2010). Thyroid hormones are well-established mediators of osmoregulation and migratory behaviours in fish, and the difference in T4 concentrations indicates that changes in thyroid hormone signalling may underlie the evolutionary and ecological divergence of migratory and non-migratory ecotypes. Questions: Is the variation in T4 concentrations present in earlier life stages where it could contribute developmentally to differences in phenotype? Do T4 concentrations change in marine ecotypes before seaward migration? Organisms: A parapatric pair of marine and stream ecotypes of threespine stickleback collected from British Columbia, Canada, and a marine ecotype collected from Washington State, USA. Methods: We collected juvenile fish of both marine and stream ecotypes on the same day in a single river to compare the whole body concentrations of T4 using radioimmunoassay. We also sampled juvenile fish of the marine ecotype in another river at three different times to determine whether these fish exhibit temporal changes in T4 concentrations before seaward migration. Results: Juvenile stickleback of the marine ecotype had higher T4 concentrations than the parapatric stream-resident juveniles. The T4 concentrations in another marine population varied slightly across sampling times before seaward migration. Conclusions: T 4 concentrations differ consistently between marine and stream ecotypes in both juvenile and adult life stages consonant with the hypothesis of evolutionary changes in thyroid signalling.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.002 |
| 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 teacher head, 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".