Molecules illuminate morphology: phylogenomics confirms convergent evolution among ‘oligotrichous’ ciliates
Bibliographic record
Abstract
'Oligotrichous' ciliates have been traditionally placed in a presumed monophyletic taxon called the Oligotrichia. However, gene sequences of the small subunit rRNA gene, and several other genes, suggest that the taxon is not monophyletic: although statistical support for this is not strong, the oligotrich Halteria grandinella is associated with the hypotrich ciliates and not with other oligotrich genera, such as Strombidium and Strombidinopsis. This has convinced some taxonomists to emphasize that morphological features strongly support the monophyly of the oligotrichs. To further test this hypothesis of monophyly, we have undertaken a phylogenomic analysis using the transcriptome of H. grandinella cells amplified by a single-cell technique. One hundred and twenty-six of 159 single-gene trees placed H. grandinella as sister to hypotrich species, and phylogenomic analyses based on a subset of 124 genes robustly rejected the monophyly of the Oligotrichia and placed the genus Halteria as sister to the hypotrich genera Stylonychia and Oxytricha. We use these phylogenomic analyses to assess the convergent nature of morphological features of oligotrichous ciliates. A particularly 'strong' morphological feature supporting monophyly of the oligotrichs is enantiotropic cell division, which our results suggest is nevertheless a convergent feature, arising through the need for dividing ciliates to undertake rotokinesis to complete cell division.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".