Climate change and the origin of migratory pathways in the Swainson's thrush,<i>Catharus ustulatus</i>
Bibliographic record
Abstract
Abstract Aim To provide a spatially explicit model of how geographic distributions at the last glacial maximum (LGM) and post‐glacial colonization routes shaped current migratory pathways in the Swainson's thrush, Catharus ustulatus , a long‐distance migratory bird. Location The Swainson's thrush breeds in boreal forest regions of the United States and Canada as well as in riparian woodlands along the Pacific coast of North America. Methods Palaeodistribution modelling is combined with mtDNA phylogeography to predict the breeding range of the Swainson's thrush at the LGM. Quantitative environmental analysis and bioclimatic modelling are used to reconstruct the most likely post‐glacial colonization pathways. A maximum likelihood method for estimating growth rates is used to approximate the relative change in population size since the LGM. Main conclusions The palaeodistribution models are concordant with the Swainson's thrush mtDNA phylogeography, suggesting that the inland and coastal groups were geographically isolated in eastern (inland) and western (coastal) regions at the LGM. Estimates of change in population size based on genetic data are remarkably consistent with estimates of change in range size, suggesting that the coastal group has undergone a 2‐ to 3‐fold demographic and range expansion, while the inland group has undergone a 6‐ to 12‐fold demographic and range expansion since the LGM. Bioclimatic analyses strongly support the hypothesis that populations expanding out of the east into previously glaciated areas in the west were undergoing a natural extension of their range by tracking the changes in climatic conditions. The combination of bioclimatic and molecular analyses is consistent with the idea that coastal and inland groups expanded from separate eastern and western regions after the LGM and that the current migratory pathway of the inland group retraces its post‐glacial colonization route.
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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 | 0.000 | 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".