POPULATION CYCLES IN THE PINE LOOPER MOTH: DYNAMICAL TESTS OF MECHANISTIC HYPOTHESES
Bibliographic record
Abstract
The forest insect pest Bupalus piniarius (pine looper moth) is a classic example of a natural population cycle. As is typical for populations that exhibit regular oscillations in density, there are several biological mechanisms that are hypothesized to be responsible for the cycles; but despite several decades of detailed study there has been no definite conclusion as to which mechanism is most important. We evaluated three hypotheses for which there was direct experimental evidence: (1) food quality (nutritional value of pine needles affected by defoliation); (2) parasitoids (trophic interactions with specialist parasitoids); and (3) maternal effects (maternal body size affects the performance of offspring). We reviewed the empirical evidence for each of these hypotheses and expressed each hypothesis in the form of a mechanistic dynamic model. We used a nonlinear forecasting approach to fit each model to three long‐term population time series in Britain that exhibit some degree of regular cycling, and we used parametric bootstrap to evaluate the significance of differences between models in their goodness of fit to the data. The results differed among the three forests: at Culbin, the parasitoid and maternal effects models fit equally well; at Roseisle, the food quality and maternal effects models fit equally well; and at Tentsmuir, the parasitoid model fit best. However, the best‐fit parasitism models required that the parasitism rate vary between nearly 0 and nearly 1 during a cycle, greatly exceeding the range of parasitism rates that have been observed in the field. In contrast, the required variation in the observable maternal quality variable (pupal mass) was within the range of empirical observations. Under mild constraints on the parasitism rate (though allowing a much wider range than has been measured in B. piniarius at any location), the fit of the parasitism model fell off dramatically. The maternal effects model then had uniformly strong support, outperforming the constrained parasitism model at all three sites and the food quality model at two; it performed slightly better than the food quality model at the remaining site. This represents the first system in which the maternal effects hypothesis for population cycles has been supported by both strong biological and dynamical evidence.
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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 | 0.011 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".