Molecular systematic relationships and evidence for a recent origin of the thermal spring endemic snails<i>Physella johnsoni</i>and<i>Physella wrighti</i>(Pulmonata: Physidae)
Bibliographic record
Abstract
The evolutionary origins of Physella johnsoni and Physella wrighti, freshwater snails endemic to thermal springs in Alberta and British Columbia, were examined by sequence comparisons of mitochondrial genes coding for segments of the large subunit ribosomal RNA (16S) and cytochrome c oxidase I (COI) with those in the closely allied species Physella gyrina. Phylogenetic reconstructions based on combined and separate analyses of the datasets identified P. wrighti as the sister taxon to a P. johnsoni + P. gyrina clade. For both gene regions there was little or no sequence variation among conspecific individuals, but a number of diagnostic differences existed between each of the species pairs. Tree topologies and estimates of sequence divergence indicate that the divergence events which separated the three species occurred rather recently and at relatively brief intervals, and it is likely that P. wrighti is the source of the ancestral population from which P. johnsoni and P. gyrina were derived. Our findings support the recognition of P. johnsoni and P. wrighti as endemic species. The populations of P. johnsoni probably separated from P. gyrina about 10 000 years ago, when glaciers retreated from the Banff area and prehistoric lake levels dropped. The limited molecular divergence between P. johnsoni and P. gyrina argues against their current placement in different subgenera within the genus Physella.
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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 | 0.001 | 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".