Temperature-dependent oxygen limitation and the rise of Bergmann's rule in species with aquatic respiration
Bibliographic record
Abstract
Bergmann's rule is the propensity for species-mean body size to decrease with increasing temperature. Temperature-dependent oxygen limitation has been hypothesized to help drive temperature-size relationships among ectotherms, including Bergmann's rule, where organisms reduce body size under warm oxygen-limited conditions, thereby maintaining aerobic scope. Temperature-dependent oxygen limitation should be most pronounced among aquatic ectotherms that cannot breathe aerially, as oxygen solubility in water decreases with increasing temperature. We use phylogenetically explicit analyses to show that species-mean adult size of aquatic salamanders with branchial or cutaneous oxygen uptake becomes small in warm environments and large in cool environments, whereas body size of aquatic species with lungs (i.e., that respire aerially), as well as size of semiaquatic and terrestrial species do not decrease with temperature. We argue that oxygen limitation drives the evolution of small size in warm aquatic environments for species with aquatic respiration. More broadly, the stronger decline in size with temperature observed in aquatic versus terrestrial salamander species mirrors the relatively strong plastic declines in size observed previously among aquatic versus terrestrial invertebrates, suggesting that temperature-dependent oxygen availability can help drive patterns of plasticity, micro- and macroevolution.
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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 | 0.002 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".