Do populations of Sclerotinia sclerotiorum across temperate and subtropical areas of the Americas share a common history?
Bibliographic record
Abstract
Isolates of S. sclerotiorum from lettuce, peanut and soybean in South America (SA) were compared with samples from lettuce from California (CA) and Ontario (total 640 isolates). Recombination over the entire population history in SA and CA was evidenced by high diversity, lack of association of markers, and net-like coalescent genealogies of DNA sequences from two loci. In contrast, Ontario samples, like previous samples from North America (NA), Europe and New Zealand, were less diverse and highly clonal, with association of independent markers and little contemporary recombination. All isolates from NA and SA were homothallic; each isolate had both mating type loci. Two new populations were identified, one comprising samples from peanut and lettuce in SA and lettuce in CA and the second comprising samples from lettuce, tomato and eggplant from SA. The coalescent analysis of a combined dataset of the samples in this study and samples from North Carolina, New York, Louisiana, Alberta and Norway from a previous study supported a genealogy with the haplotype with the longest coalescence to the most recent common ancestor from NA samples (North Carolina and Alberta), followed by a haplotype from the SA-California population. Our preferred hypothesis for the origin of the species in the Americas is two introductions, one via Northern European human immigration to NA and the other via Southern European immigration to SA. We suggest that S. sclerotiorum was introduced to California from SA during the Gold Rush, ca. 1850. But where did the species originate? If the species evolved in the Old World, for example in Asia, introduction from Asia to NA or SA is possible, perhaps via Europe. A more ancient, alternative hypothesis is origin of the species in the Americas, with escape from Pleistocene refugia in both the Northern and Southern Hemisphere. This hypothesis is consistent with the relationship of the two oldest haplotypes to the boundaries of Pleistocene glaciation.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 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".