Species limits, phylogeny and niche evolution: a case study in «Carex» (Cyperaceae)
Bibliographic record
Abstract
Two conflicting processes are believed to influence the relationship between taxonomic and ecological diversity: adaptive radiation and niche conservatism. No consensus has yet emerged regarding the conditions that favour conservatism of traits due to common ancestry over adaptive radiation and the resulting ecological divergence. Carex is an ideal group for studying these phenomena, as it is incredibly diverse taxonomically and ecologically, and includes many recently formed lineages. I chose a group of eight closely related Carex taxa from eastern North America as the focus of my study. Multivariate analysis of 30--33 morphological variables measured on 456 plants from 110 populations confirmed the existence of eight different entities. Analysis of 141 AFLP fragments from 435 plants from the same populations revealed the same eight groups. I recognise each of these taxa as distinct species. These include C. roanensis, a globally rare species whose taxonomic status had been questioned, and C. complanata and C. hirsutella, a pair of species that some authors had considered a single variable taxon. Six previously unknown sterile or nearly sterile hybrids are documented with a combination of morphology, restriction fragment, and AFLP data. Parsimony and distance analyses of the AFLP data failed to fully resolve the phylogeny of this group, but did establish consistent estimates of the relative evolutionary distances among species. Morphology does not reflect the phylogenetic relationships in this group. There were significant differences among species for niche measures calculated from climate variables, ecological niche models, and local habitat variables. Niche divergence was significantly correlated with phylogenetic distance, indicating niche conservatism is an important process governing ecological evolution in this group. Furthermore, the shape of the relationship suggested that phylogenetic distance limits the maximum possible ecological divergence, but with
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".