Ecological and Evolutionary Diversification Within the Genus <I>Carex</I> (Cyperaceae): Consequences for Community Assembly in Subarctic Fens
Bibliographic record
Abstract
Abstract The concept of limiting similarity predicts that closely related taxa are less likely to co-occur than expected by chance. The degree to which the phylogenetic relatedness in plant communities is in accord with limiting similarity has been little tested at the scale where the consequences of adaptive differentiation during speciation should be most evident: the scale of neighboring, congeneric plants within a community. To quantify species co-occurrence patterns in relation to environment, we sampled sedge species, their rooting level relative to the water table, and the water pH in 2,124 0.25 m2 quadrats distributed across 29 subarctic fens in the central Labrador Peninsula. We estimated phylogenetic relationships using four DNA regions (ETS, ITS, matK, trnL-trnF) for all species of Carex (42), Eriophorum (6), and Trichophorum (2) in the region, of which 21, four, and two, respectively, occurred in the sampled fens. We demonstrate that closely related species of Carex are less likely to co-occur than expected by chance using 1) a probabilistic method to test the significance of pairwise co-occurrence patterns of species, and 2) linear mixed modeling to relate these patterns to phylogenetic relationships and ecological tolerances along gradients of substrate pH and rooting level in relation to the water table. The results also indicate that suites of species with significant mutual pairwise co-occurrence belong to distant lineages within the Cariceae-Dulichieae-Scirpeae clade of Cyperaceae and have stabilizing niche differences. We suggest that niche differentiation during the evolution and diversification of a clade of wetland Carex species over the past few million years, especially during the dynamic glacial cycles of the Pleistocene, has resulted in diverse sedge communities that share space and resources in harsh northern peatland 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 | 0.000 | 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".