The universal evolutionary and ecological significance of 20 oC
Bibliographic record
Abstract
We connect evidence that 20 oC is the most stable temperature for cellular processes with macroecological observations. Examples show that temperatures warmer than ~20 oC result in decreases in: aquatic species’ tolerance to low oxygen; marine pelagic and benthic algal productivity; pelagic and benthic predation rates; global species richness in pelagic fishes, plankton and benthic invertebrates; and genetic diversity; but increased extinctions in the fossil record. The realised thermal niche of reef fishes and invertebrates globally is narrowest among species with distributions centred on 20 oC, as also seen in microbes. While many species have evolved to live at warmer and colder temperatures, most species live at, and extinctions in the fossil record across seven phyla were lower at, 20 oC. The mathematical “Corkrey” model, which predicts that thermal breadth should be minimized and species richness maximised at 20 oC across all Domains of life, provides an explanation for this “20 oC effect”. A literature search found highest species richness at ~20 oC across life in air and water, including animals, plants and microbes. That life seems centred around ~20 oC implies fundamental constraints that compromise the ability of extant tropical species to adapt to higher temperatures.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".