An unexpected recent ancestor of unisexual <i>Ambystoma</i>
Bibliographic record
Abstract
Previous research has shown that members of the unisexual hybrid complex of the genus Ambystoma possess a mitochondrial genome that is unrelated to their nuclear parental species, but the origin of this mitochondrion has remained unclear. We used a 744-bp fragment of the mitochondrial gene cytochrome b within a comparative phylogenetic framework to infer the maternal ancestor of this unisexual lineage. By examining a broader range of species than has previously been compared, we were able to uncover a recent maternal ancestor to this complex. Unexpectedly, Ambystoma barbouri, a species whose nuclear DNA has not been identified in the unisexuals, was found to be the recent maternal ancestor of the individuals examined through the discovery of a shared mtDNA haplotype between the unisexuals and A. barbouri. Based on a combination of sequence data and glacial patterning, we estimate that the unisexual lineage probably originated less than 25 000 years ago. In addition, all unisexuals examined showed extremely similar mtDNA sequences and the resultant phylogeny was consistent with a single origin for this lineage. These results confirm previous suggestions that the unisexual Ambystoma complex was formed from a hybridization event in which the nuclear DNA of the original maternal species was subsequently lost.
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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 | 0.000 |
| 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".