Explaining the disjunct distributions of austral plants: the roles of Antarctic and direct dispersal routes
Bibliographic record
Abstract
Abstract Aim Dispersal explains the disjunct distributions of many austral plant lineages. However, the role of Antarctica is largely uncertain and the routes of dispersal have remained speculative. Based on niche conservatism we can make predictions about the timing of disjunction establishment, as well as the availability of direct transoceanic, Antarctic stepping‐stone, and out‐of‐Antarctica dispersal routes over time. We evaluate these predictions using molecular divergence time estimates for the establishment of disjunct distributions across multiple plant lineages. Location Southern Hemisphere. Methods We estimated the timing of disjunction establishment and determined habitat affinities for 72 austral plant groups. We used Wilcoxon rank sum tests to compare the timing of disjunction establishment between cold and temperate climate lineages for the full data set, as well as within several subsets. We compared our results with those from a literature survey. Results As niche conservatism predicts, the timing of disjunction establishment in cold and temperate climate austral lineages is consistent with the availability of the corresponding habitats over time. Our results also suggest that disjunction establishment has involved a combination of Antarctic and direct dispersal routes. For cold climate lineages, both out‐of‐Antarctica and direct dispersal routes are required to explain the observed estimates, while stepping stone routes cannot be ruled out. It appears that for these lineages the importance of the three dispersal routes differs with environmental, geographical and temporal context. Main conclusions Both direct and Antarctic dispersal routes are necessary to explain the establishment of contemporary austral distributions. Evidence that some taxa were, until recently, restricted to Antarctica changes how we view the evolutionary histories of austral floras and the lineages they contain. Moreover, that we detect differences in the importance of alternative dispersal routes suggests that long‐distance plant dispersal processes can be explicitly incorporated into models of climate change response.
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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 | 0.001 | 0.003 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".