Physiological Tradeoffs Underlie the Evolution of Hypoxia Tolerance and Exercise Performance in Fish
Bibliographic record
Abstract
There is a frequently observed tradeoff between hypoxia tolerance and exercise performance in fish, even though both of these traits are often associated with a high O 2 transport capacity. We examined the physiological basis for this tradeoff in four species of bass and sunfish from the family Centrarchidae. Hypoxia tolerance was greatest in rock bass, intermediate in pumpkinseed sunfish and bluegill sunfish, and lowest in largemouth bass, based on measurements of critical O 2 tension (P crit ) and the O 2 tension at loss of equilibrium. The least hypoxia‐tolerant species had the highest critical swimming speed (U crit ) and maximal O 2 consumption rate during swimming, and suffered the greatest decrease in U crit during exercise in hypoxia, consistent with there being a tradeoff between hypoxia tolerance and exercise performance. Some traits appeared to contribute to both hypoxia tolerance and exercise performance, as reflected by the traits that were highest in both rock bass and largemouth bass, such as the gas‐exchange surface area of the gills and the enzyme activities of lactate dehydrogenase and the gluconeogenic enzyme phosphoenolpyruvate carboxykinase in the liver. Some other traits were uniquely associated with hypoxia tolerance (pyruvate kinase and lactate dehydrogenase activities in the heart) or exercise performance (capillarity and fibre size of the axial swimming muscle). Therefore, the cumulative influence of a variety of respiratory and metabolic traits likely underlies the physiological tradeoffs associated with the evolution of hypoxia tolerance and exercise performance in fish. (Supported by NSERC of Canada)
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 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".