Phylogeny and Historical Biogeography of the Genus <I>Platanus</I> as Inferred From Nuclear and Chloroplast DNA
Bibliographic record
Abstract
Abstract Phylogenetic analyses of DNA sequences of six species of Platanus were conducted to estimate species relationships and analyze biogeographic history. On the basis of a broader analysis of the third exon of the nuclear gene LEAFY, the root node for the genus was confirmed to fall between subg. Castaneophyllum (P. kerrii) and the species of subg. Platanus. Separate phylogenetic analyses of the nuclear ribosomal ITS region, the 3′ region of the second intron of LEAFY, and the chloroplast region trnT-trnL intergenic spacer provided various levels of resolution, and the combined data yielded a fully resolved set of relationships within subg. Platanus. Two major clades were identified: one with species from Europe (EUR) and western North America (WNA) (P. orientalis, P. racemosa s.l.), the other with species from eastern North America (ENA; US and Canada) and eastern Mexico (EMEX) (P. mexicana, P. occidentalis, and P. rzedowskii). Within subg. Platanus, six subclades corresponded to previously recognized taxa, and one accession may be of hybrid origin. The historical biogeography of Platanus was interpreted using phylogenetic pattern, estimates of divergence times, the fossil record, and climate reconstructions. The pattern of relationships was consistent with a hypothesis of vicariance and the oldest divergence between taxa within the set of area relationships of ((WNA + EUR), (ENA + MEX)) suggested an initial barrier affecting taxa that are now mostly confined to North America. The second oldest divergence within subg. Platanus involves the intercontinental disjunction of semi-arid species from WNA + EUR, which diverged by at least 15 MYBP, consistent with the Madrean-Tethyan hypothesis. Calibrated phylogenies were used to estimate divergence times for five more recent intracontinental disjunctions. These times correlated with the timing of geological events in southwestern North America and northern Latin America.
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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".