Population phase-dependent niche requirements may limit outbreaks of the range-expanding mountain pine beetle in the western boreal forest
Bibliographic record
Abstract
Climate warming has exacerbated hyperepidemics by irruptive species in habitats outside their historic range. However, range expansion during epidemics may not result in long-term persistence or proliferation in novel habitats if requirements of sub-outbreak (endemic) populations differ from those of epidemic populations. Mountain pine beetle ( Dendroctonus ponderosae ), an irruptive bark beetle in western North American lodgepole pine forests, recently breached the Rocky Mountain geoclimatic barrier and expanded into evolutionarily naïve lodgepole pine and jack pine forests. We examined its potential to naturalize in newly invaded habitats by quantifying biotic interactions with trees known to predispose hosts to endemic beetle populations in 16 stands along a transect from the native range to eastern edge of the invasion front. The density of trees susceptible to endemic mountain pine beetle was 3 × greater in native and naïve lodgepole pine than in jack pine. The quality of the endemic niche in novel habitats for D. ponderosae , especially in jack pine, was further constrained by greater competition with other subcortical species. In newly invaded jack pine forests, 50 % of defensively compromised trees were co-occupied by woodboring beetle species versus 20 % in naïve lodgepole and < 1 % in historical lodgepole pine forests, and when woodborers were present, 17 × , 6 × , and 0.25 × more phloem was consumed, respectively. Thus, the niche available to endemic D. ponderosae in western boreal jack pine forests appears to be constrained by both lower resource availability and higher competition, suggesting recurrent outbreaks originating there are unlikely. In contrast, novel lodgepole pine habitats appear suitable for endemic populations, and may generate outbreaks during favorable conditions. • Niche requirements distinct for endemic and epidemic mountain pine beetles. • Persistence in novel habitats requires an available endemic niche. • Endemic niche assessed in native lodgepole and newly invaded jack pine habitats. • Endemic niche in jack pine constrained by low resources and high competition.
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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 | 0.000 |
| 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) | 0.001 | 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".