MEASURING THE ALLEE EFFECT: POSITIVE DENSITY DEPENDENCE IN SMALL MAMMALS
Bibliographic record
Abstract
Positive density dependence (the Allee effect) has numerous implications for the dynamics, distribution, and conservation of populations, but has been considered difficult to measure because it should occur only at small population sizes. Theories of density-dependent habitat selection provide a simple solution. Allee effects produce erratic habitat selection where individuals that initially pack into the better habitat flow rapidly into the poorer one at a threshold density. The instability creates a hiatus or “hole” in abundance along habitat isodars (graphs of density assuming ideal habitat selection). The presence of an Allee effect can be detected easily by calculating the exact probabilities of the observed frequency of data points in the hiatus area with that expected if fitness is positively density dependent at low density. Tests of the theory using rodents occupying mesic and xeric habitats in Canada's Rocky Mountains reveal a clear example of the Allee effect in red-backed voles, and hint at a similar effect in deer mice. The tests suggest that populations of small mammals may frequently reach low densities where positive density dependence in fitness may play a significant role in population persistence.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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; both teacher heads agree on what is shown here.
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".