Direct long‐distance dispersal best explains the bipolar distribution of <i>Carex arctogena</i> (<i>Carex</i> sect. <i>Capituligerae</i>, Cyperaceae)
Bibliographic record
Abstract
Abstract Aim The bipolar disjunction, a biogeographical pattern defined by taxa with a distribution at very high latitudes in both hemispheres (> 55° N; > 52° S), is only known to occur in about 30 vascular plant species. Our aim was to use the bipolar species Carex arctogena to test the four classic hypotheses proposed to explain this exceptional disjunction: convergent evolution, vicariance, mountain‐hopping and direct long‐distance dispersal. Location Arctic/boreal and temperate latitudes of both hemispheres. Methods A combination of molecular and bioclimatic data was used to test phylogeographical hypotheses in C. arctogena . Three chloroplast markers ( atp F –atp H , matK and rps16 ) and the nuclear ITS region were sequenced for all species in Carex sections Capituligerae and Longespicatae ; Carex rupestris , C. obtusata and Uncinia triquetra were used as outrgroups. Phylogenetic relationships, divergence‐time estimates and biogeographical patterns were inferred using maximum likelihood, statistical parsimony and Bayesian inference. Results Carex sections Capituligerae and Longespicatae formed a monophyletic group that diverged during the late Miocene. Two main lineages of C. arctogena were inferred. Southern Hemisphere populations of C. arctogena shared the same haplotype as a widespread circumboreal lineage. Bioclimatic data show that Southern and Northern Hemisphere populations currently differ in their ecological regimes. Main conclusions Two of the four hypotheses accounting for bipolar disjunctions may be rejected. Our results suggest that direct long‐distance dispersal, probably southwards and mediated by birds, best explains the bipolar distribution of C. arctogena .
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| 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".