Repeatability of critical thermal maximum (CTmax) in two freshwater ectotherms across contexts
Bibliographic record
Abstract
Critical thermal maximum (CT max ) is the most widely used method for quantifying acute upper thermal limits in ectotherms. CT max protocol exposes animals to a consistent rate of environmental warming until they lose motor function. CT max has been used to assess intraspecific variation among life stages, populations, or as a function of body size, often with the assumption that it is a durable and heritable trait at the individual level. The existence of within-individual repeatability of CT max has been used to infer the potential for thermal adaptation via the positive correlation between the repeatability of a trait and its heritability. However, for how widely used CT max has become, surprisingly few studies have quantified within-individual repeatability in aquatic ectotherms, and none have assessed repeatability across contexts. We examined the cross-context repeatability of CT max in two freshwater ectotherms (one decapod crustacean and one teleost fish): rusty crayfish Faxonius rusticus (n = 31) and pumpkinseed Lepomis gibbosus (n = 38). Individual repeatability was measured on a weekly basis across multiple trials (n = 5 pumpkinseed CT max measurements, n = 7 rusty crayfish) that varied in acclimation temperature, oxygen saturation, and salinity. CT max was most strongly influenced by acclimation temperature. Repeatability varied based on the statistical approach and between the two species. Pumpkinseed repeatability across contexts was moderate ( ca. 0.4), similar to previous reports on within-context CT max repeatability studies in fishes. In rusty crayfish, repeatability was much lower ( ca . 0.16). This suggests CT max repeatability may be both taxon- and context-dependent, thus further investigation into repeatability is needed across species for this important and widely used trait. • Repeatability of upper thermal tolerance was taxon- and context-dependent • Pumpkinseed repeatability across contexts was moderate • Crayfish repeatability across contexts was low • Repeatability differed based on statistical approach • Acclimation temperature drove changes in tolerance among treatments for both species
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| 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 teacher head, 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".