Phylogeography of "glacial relict" <i>Gammaracanthus</i> (Crustacea, Amphipoda) from boreal lakes and the Caspian and White seas
Bibliographic record
Abstract
As with a number of "glacial relict" crustacean genera, species of Gammaracanthus are vicariously distributed in circumarctic coastal waters, in boreal freshwater lakes, and in the Caspian Sea. Various hypotheses have been invoked to explain the origins and diversity of the non-marine taxa. Data on 28 allozyme loci and 558 bp of the mitochondrial COI gene demonstrate a close affinity between G. caspius of the Caspian Sea and G. aestuariorum of the White Sea area (Nei's allozyme distance D = 0.09, COI sequence divergence d = 5%), and a threefold divergence of the two from the Fennoscandian freshwater G. lacustris (D = 0.33, d = 12%). The relative molecular affinities agree with morphological evidence but contradict the idea of a common ancestry of the non-marine taxa, rather they suggest two independent invasions of continental waters. The generally low molecular divergence refutes the recently suggested generic splitting of Gammaracanthus. Previous speculations of an affinity of Gammaracanthus to the Baikalian acanthogammarids or to the Eusiroidea are not substantiated. The interspecific phylogeographic structure of Gammaracanthus is not concordant with that of other "glacial relict" crustacean genera. Phylogeographically, Gammaracanthus seems to match with the genus Monoporeia alone, rather than with Pontoporeia sensu lato.
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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 | 0.001 | 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 | 0.005 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".