Divergence, hybridization, and diversification in an eastern North American willow syngameon
Bibliographic record
Abstract
Present-day patterns of genetic diversity and phylogeography are influenced by various factors, with hybridization and historical climate changes often pivotal. The Salix genus presents an ideal case study for these dynamics because of the large numbers of hybridizing species. This study investigates the intricate hybridization dynamics within a quadra-species hybrid syngameon that includes Salix nigra and three closely related species: S. amygdaloides, S. gooddingii, and S. caroliniana. Employing sequence capture techniques, we analyzed 6646 975 single nucleotide polymorphisms (SNPs) across 265 individuals from 18 populations to investigate population structure, genetic diversity, phylogenetic relationships, demography, and hybridization patterns. Significant hybridization was observed between S. nigra and its close relatives. Hybridization can account for up to 31% of the genome in hybrid-zone populations of S. nigra; nucleotide diversity is up to 56% higher than in allopatric populations, thereby strongly shaping population structure and genetic diversity. Demographic analyses suggest a model of ongoing gene flow throughout the speciation process. Species distribution modeling indicated that currently allopatric species likely had overlapping distributions in the past, which allowed past hybridization. This study illuminates how historical glaciation in North America influences the timing and location of hybridization and, in turn, shapes contemporary geographic patterns of genetic diversity.
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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 | 0.001 | 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".