Ribosomal DNA sequence polymorphism and the delineation of two ascosporic yeast species: Metschnikowia agaves and Starmerella bombicola
Bibliographic record
Abstract
The relationship between mating success and sequence divergence in the internal transcribed spacer (ITS)/5.8S-D1/D2 rDNA region was examined in isolates tentatively assigned to Metschnikowia agaves and Starmerella bombicola. Both species are haplontic and heterothallic, such that the formation of mature asci can be used as a measure of genetic compatibility. Parsimony haplotype network analysis and mating success confirmed that all known isolates of M. agaves are conspecific. The previously reported D1/D2 polymorphism of five substitutions was not corroborated; the maximum divergence observed between any two strains was three substitutions, four with ITS. Of 39 putative S. bombicola strains, 36 formed an ITS-D1/D2 haplotype network using the 95% criterion. Thirty-five strains could mate with one or more compatible partner. The excluded strains did not mate. Mature asci arose from crosses between individuals differing by as many as five, but not six or seven substitutions in the D1/D2 domain. All strains capable of mating formed mature asci with at least one partner and all network members could be linked to another member by three or fewer substitutions. These results support the use of sequence divergence as a criterion for species delineation, but caution against describing poorly sampled species solely on the basis of that criterion.
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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) | 0.000 | 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 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".