Evidence for ancient selective sweeps followed by differentiation among three species of <i>Sphyrapicus</i> sapsuckers
Bibliographic record
Abstract
Abstract Speciation occurs when gene pools differentiate between populations, but that differentiation is often highly heterogeneous across the genome. Understanding what parts of the genome are more prone to differentiation can inform us about genomic regions and evolutionary processes that may be central to the speciation process. Here, we study genomic variation among three hybridizing species of North American woodpecker: red-breasted, red-naped, and yellow-bellied sapsuckers ( Sphyrapicus ruber, S. nuchalis, and S. varius ). We use whole genome resequencing to measure genetic variation among these species and to quantify how the level of differentiation varies across the genome. We find that regions of high relative differentiation between species ( F ST ) tend to have low absolute differentiation between species (π B ), indicating that regions of high relative differentiation often have more recent between-population coalescence times than regions of low relative differentiation do. Most of the high- F ST genomic windows are found on the Z chromosome, indicating this sex chromosome is particularly important in sapsucker differentiation and potentially speciation. These results are consistent with a model of speciation in which selective sweeps of globally advantageous variants spread among partly differentiated populations, followed by differential local adaptation of those same genomic regions. We propose that sapsucker speciation may have occurred primarily via this process occurring on the Z chromosomes, resulting in genetic incompatibilities involving divergent Z chromosomes.
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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 | 0.000 |
| 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".