HISTORICAL BIOGEOGRAPHY OF THE AUSTRAL HORNWORT GENUS PHAEOMEGACEROS (DENDROCEROTACEAE, ANTHOCEROTOPHYTA)
Bibliographic record
Abstract
The transoceanic disjunct distributions between Australasia and Austral America have been observed in many plant groups. The processes behind these disjunct distributions remain a source of debate due to differences in species vagility, biogeographical history, and complex geological and climatic changes. We address the phylogenetic relationships and biogeographical history of the austral hornwort genus Phaeomegaceros based on eight molecular markers from the three genomes (nuclear: phytochrome, mitochondrial: nad5, and chloroplast: rbcL, trnL intron, trnL-trnF spacer, rps4 gene, rps4-trnS spacer, and matK gene). With ten taxa based on morphological and molecular data, the three phylogenetic analyses supported the genus Phaeomegaceros as monophyletic. Phaeomegaceros is composed of two major clades corresponding to the New Zealand species, which presents a conspicuous trilete mark with one depression in the middle of the spore’s proximal face, and the Austral American species, which lack this middle depression. Dating and biogeographical analyses indicate that the Phaeomegaceros ancestral area was New Zealand and Antarctica in the Late Cretaceous (53.51 Ma, HPD 95% = 31.64–72.63). While Austral American species diverged during the Eocene. We speculate that climatic fluctuations in the Antarctic continent during the middle to late-Miocene led to the isolation of Phaeomegaceros taxa with both processes (dispersal events and vicariance) acting on the independent evolution of the disjunct clades. Furthermore, recent diversification of Phaeomegaceros taxa in Austral America and range expansion to northern Andes and oceanic islands, are explained by dispersal events and subsequent cladogenesis coinciding with the uplift of the Andes and the formation of volcanic oceanic islands (Juan Fernandez and Tristan da Cunha).
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".