Molecular phylogenetic analysis of the north-temperate Labrador Teas (Ericaceae: Rhododendron Subsect. Ledum) suggests a complex genetic history
Bibliographic record
Abstract
The Labrador teas are a group of nearly circumboreal shrubs or sub-shrubs inhabiting damp habitats. The 4–7 currently recognized species are classified within Rhododendron subg. Rhododendron section Rhododendron subsect. Ledum. In floral characters, these species are extremely similar. In vegetative characters, species limits in the Labrador teas have been difficult to determine because many of the traditionally used morphological characters vary continually across the geographic range. This study investigated evolutionary history and preliminary consideration of some species boundaries in the Labrador teas using DNA sequence data from five molecular markers to generate a preliminary phylogeny of R. subsect. Ledum. Data were analyzed using Maximum Parsimony, Maximum Likelihood and Bayesian methods. The nuclear data indicate a monophyletic subsect. Ledum, but chloroplast data indicate that the North American taxa have an evolutionary history separate from the European and Asian taxa, suggesting that one or both lineages of subsect. Ledum may be of hybrid origin. Additionally, our analyses suggest that taxa combined in recent treatments (i.e. Rhododendron tomentosum) represent separate lineages and should be recognized as distinct instead of included within more broadly defined species, however our current level of sampling cannot completely resolve this issue. This study lays the groundwork for future phylogenetic studies within subsect. Ledum, illustrating the need to sample more intensively across taxa in order to capture what appears to be a complex genetic and biogeographic history.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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".