A temporal dimension to the stress gradient hypothesis for intraspecific interactions
Bibliographic record
Abstract
Space and time are the two fundamental drivers of ecological dynamics. Studies exploring the Stress gradient hypothesis (SGH) – which predicts that the patterns of interspecific interactions shift from negative to positive with increasing environmental severity – conceptualize environmental severity predominantly from a spatial perspective. Here, from a temporal perspective and for intraspecific interactions, we asked: do the predictions of the SGH at the intraspecific level apply to seasonal change in environmental severity? We conducted a field experiment, which was complemented by a two‐year field survey of natural populations of the non‐native biennial forb Alliaria petiolata at the Koffler Scientific Reserve, Ontario, Canada. In both experiment and field survey studies we found statistically significant negative density‐dependent survival in the productive summer period and positive density‐dependent survival over the severe winter period. Effects were stronger in the field experiment than in the survey of natural populations. We suggest that the SGH at the intraspecific level may be applicable to seasonal variation in environmental severity, though our ability to detect its effect in natural communities may depend on other factors such as species dominance and environmental heterogeneity.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".