Trans‐Arctic speciation of Florideophyceae (Rhodophyta) since the opening of the Bering Strait, with consideration of the “species pump” hypothesis
Bibliographic record
Abstract
Abstract Aim The opening of the Bering Strait initiated significant biotic interchange that is postulated to have played a major role in phylogeographical patterns of northern marine flora and fauna. In addition, the “species pump” hypothesis asserts that glaciation events promoted speciation due to repeated isolation of populations over the past 2.6 million years. Here, trans‐Arctic speciation events in red marine macroalgae (Florideophyceae) were assessed using time‐calibrated phylogenies, and the applicability of the “species pump” hypothesis was considered. Location Species records and sequence data for trans‐arctic genera of marine macroalgae were amalgamated and supplemented with sampling from the Northwest Atlantic, Northern Alaska (Beaufort Sea), Norway, and Nome, Alaska (Bering Sea; 2014–2017). Methods Bayesian and maximum likelihood phylogenies were variously built using the 5′ end of the cytochrome c oxidase subunit I gene (COI‐5P), and/or the full‐length nuclear internal transcribed spacer region (ITS), and/or the ribulose‐1 5‐biphosphate carboxylase large subunit gene (rbcL), and nodes were timed using calibrated COI‐5P and rbcL molecular clocks. The final dataset represented approximately 184 species, broadly representing 14 trans‐arctic lineages. Results Pacific to Atlantic migration and subsequent speciation was inferred in 11 cases, whereas the opposite scenario, atlantic to pacific, was inferred once; only three speciation events appeared to occur during the Pleistocene. Main conclusions Our results are in agreement with previous studies in that trans‐arctic speciation events postdated the opening of the Bering Strait with a clear pacific to atlantic bias. Evidence for the “species pump” (as applied to trans‐arctic interchange) was lacking given the frequency of trans‐arctic speciation events was not amplified during the Pleistocene.
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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 | 0.001 | 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".