Fitness dynamics within a poplar hybrid zone: I.<scp>P</scp>rezygotic and postzygotic barriers impacting a native poplar hybrid stand
Bibliographic record
Abstract
Hybridization and introgression are pervasive evolutionary phenomena that provide insight into the selective forces that maintain species boundaries, permit gene flow, and control the direction of evolutionary change. Poplar trees (Populus L.) are well known for their ability to form viable hybrids and maintain their distinct species boundaries despite this interspecific gene flow. We sought to quantify the hybridization dynamics and postzygotic fitness within a hybrid stand of balsam poplar (Populus balsamifera L.), eastern cottonwood (P. deltoides Marsh.), and their natural hybrids to gain insight into the barriers maintaining this stable hybrid zone. We observed asymmetrical hybrid formation with P. deltoides acting as the seed parent, but with subsequent introgression biased toward P. balsamifera. Native hybrids expressed fitness traits intermediate to the parental species and were not universally unfit. That said, native hybrid seedlings were absent from the seedling population, which may indicate additional selective pressures controlling their recruitment. It is imperative that we understand the selective forces maintaining this native hybrid zone in order to quantify the impact of exotic poplar hybrids on this native system.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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) | 0.000 | 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".