Lineage-specific phylogenetic structure of boreal habitats suggests different assembly processes across phylogenetic and spatial scales
Bibliographic record
Abstract
Understanding how plant communities are assembled is critical to explaining the functioning of ecosystems and the maintenance of biodiversity. The phylogenetic distance among species in a community (community phylogenetic structure) has been used to infer deterministic and stochastic assembly processes, albeit with criticisms. However, the effect of the phylogenetic scale (old versus young lineages) and spatial scale on measures of community phylogenetic structure are rarely tested especially in the boreal biome, yet essential to unravel different assembly processes that might operate across species in a community. We examined lineage-specific phylogenetic structure of six plant communities defined at the habitat scale, and the phylogenetic structure of communities defined at a plot level scale (1m2). We obtained vascular plant species lists for six habitats (arctic-alpine barren, bog, fen, kalmia barren, limestone barren, and serpentine barren) on the island of Newfoundland, Canada, and 73 permanent vegetation plots within three of the above habitats to estimate their mean pairwise phylogenetic distance standardized for sample size (SES-MPD). Contrary to the expectation under the stress-dominance hypothesis of phylogenetic clustering in challenging boreal environments, the majority of clades had random phylogenetic structure. However, we observed a pattern consistent across most habitats of a shift from phylogenetic clustering at the deepest nodes of the angiosperms to no phylogenetic structure at shallower nodes, suggesting that different assembly processes may be operating at different phylogenetic scales within a habitat. As expected, all vegetation plot communities at a fine spatial scale showed strong phylogenetic overdispersion likely explained by biotic interactions. Our lineage-specific approach to estimate SES-MPD proved useful to outline testable hypotheses on the evolution and role functional traits play in community structure and assembly of boreal habitats
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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".