Glaciation as an historical filter of below‐ground biodiversity
Bibliographic record
Abstract
Abstract Aim The latitudinal gradient in species richness is one of the most studied biodiversity patterns. Here we explore a north–south gradient in earthworm diversity, and evaluate the importance of current and historical filters in shaping the distribution of present‐day below‐ground species richness. Location France. Methods Using high resolution data on earthworm distributions across France, we document the latitudinal gradients in alpha (α), beta (β) and gamma (γ) diversity. We relate these gradients to species' traits, taxonomic aggregation and co‐occurrence patterns, and correlate them with the present climate and the history of glaciation in Europe. Results We found that γ‐diversity decreases from south to north whereas α‐diversity increases along the same latitudinal gradient. Communities in formerly glaciated regions are composed of smaller, more mobile species and show trait and taxonomical aggregation. In more southerly populations, which did not experience glaciation, earthworm species are larger, have smaller geographical ranges, and communities demonstrate a decrease in species co‐occurrence resulting in lower local species richness. Main conclusions We show that species richness gradients can present different – sometimes opposite – latitudinal trends depending upon the scale of the analysis. This scale dependence sheds new light on the underlying causes of global biodiversity gradients. The opposing latitudinal trends of the different components of diversity suggest that recolonization following glaciations during the Pleistocene acted as an environmental filter, and that competitive exclusion may be a more dominant ecological force in these former refugial areas. Overall our results show that past climate changes have left a deep footprint on present‐day earthworm diversity patterns, from community to macroecological scales, and that different mechanisms of earthworm community assembly may predominate at different latitudes.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".