Developmental delay in shivering limits thermogenic capacity in juvenile high-altitude deer mice (<i>Peromyscus maniculatus</i>)
Bibliographic record
Abstract
Many endotherms native to cold and hypoxic high altitude (HA) environments have evolved a highly vascularized and aerobic skeletal muscle. This specialized muscle phenotype contributes via shivering to an enhanced capacity for aerobic thermogenesis (cold-induced VO2max). However, it is unclear how selection at HA for shivering thermogenesis acts early in the development of small altricial mammals, which are born with immature skeletal muscles and without the capacity for homeothermic endothermy. We have previously shown that postnatal maturation of brown adipose tissue and non-shivering thermogenesis is delayed in HA native deer mouse pups (Peromyscus maniculatus). To assess if HA adaptation has also altered the developmental program of skeletal muscle and shivering thermogenesis, we used laboratory-reared descendants of deer mice native to low (430 m a.s.l) and high (4350 m a.s.l.) altitude and a low altitude (LA) congeneric outgroup (P. leucopus). We found that LA juveniles were able to shiver robustly at 2 weeks after birth. However, HA juveniles were unable to shiver at this point, resulting in a 30% lower capacity for thermoregulation compared to lowlanders. It was only at 27 days after birth that HA juveniles had established the aerobic muscle phenotype characteristic of HA adults and a superior cold-induced VO2max compared to LA mice of the same age. The capacity for shivering may be delayed in HA mice to allow energy to be allocated to other important processes such as growth.
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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 | 0.001 |
| 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".