Lineage origin and expansion of a Neotropical migrant songbird after recent glaciation events
Bibliographic record
Abstract
Birds of the Northern Hemisphere often harbour the genetic signature of postglaciation expansion but analyses identifying the location of refugia and the directionality of expansions are rare. Here we explore the evolutionary history of yellow warbler lineages, focusing on how these lineages recolonized their current range. We genotyped samples from 696 yellow warblers via direct sequencing of a 333-bp control region I mitochondrial DNA fragment or lineage-specific genotyping. Phylogenetic analysis revealed two monophyletic clades: a highly migratory group including previously identified eastern and western lineages and a less migratory group including a lineage consisting of tropical residents and a new 'southern' lineage localized in southwest United States. We then modelled the expansion of the eastern and western lineages, identified the location of potential refugia and assessed the importance of migration as a historical factor promoting gene flow. The expansion of the eastern lineage proceeded from a main refugia in the eastern United States, with possible contribution of an additional local refugia. In the western lineage, the expansion proceeded from a single refugia possibly located in western United States. Because two lineages overlapped to varying degrees in central North America, we suggest that the Canadian Prairies offered a bridge of riparian habitats where the lineages met after glacier retreat, while the US Central Great Plains acted as a barrier that limited secondary contact. Finally, gene flow was more important along the north-south axis of migration than away from it, suggesting spring migration played a role in the dispersal of lineages.
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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".