Geographical origins of North American <i>Rhodiola</i> (Crassulaceae) and phylogeography of the western roseroot, <i>Rhodiola integrifolia</i>
Bibliographic record
Abstract
Abstract Aim Complex migration histories with repeated range shifts during the Pleistocene characterize many arctic–alpine plants. Identifying these patterns provides insight into the causes of current distributions and possible responses to climate warming. We investigated patterns of genetic variation in North American species of a widespread Northern Hemisphere plant group to test different hypotheses of origin and refugial persistence. Location North America. Methods We used a phylogeographical approach to investigate the geographical origins of North American Rhodiola , especially the widespread western species R. integrifolia . Populations were sampled over much of the North American range (66 of R. integrifolia , 6 of R. rhodantha and 4 of R. rosea ). We performed maximum likelihood phylogenetic analyses on sequences of the nuclear internal transcribed spacer (ITS) region and the plastid trn H –psb A intergenic spacer, and analysed geographical patterns of haplotype distribution and genetic diversity using plastid restriction‐site and sequence data from all populations. Results Separate lineages of Rhodiola dispersed into North America via the Bering Strait ( R. integrifolia and R. rhodantha ) and amphi‐Atlantic regions ( R. rosea ). Genetic patterns within R. integrifolia indicate southward spread from Beringia, with subsequent persistence in both northern and southern refugia. Rhodiola integrifolia and the regional endemic R. rhodantha show evidence of past hybridization (resulting in chloroplast capture) where their ranges overlap in the southern Rocky Mountains. However, phylogenetic evidence suggests that both species are closely related to Asian taxa and probably migrated independently into North America. Main conclusions The current geographical distributions and genetic structure of North American Rhodiola are the result of a complex history including multiple migrations into North America, persistence in multiple refugia during glaciations, and past hybridization. This complexity of processes within one group underscores the diverse history of arctic–alpine plants and the likelihood of divergent responses to changing environments.
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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".