Thermal flexibility is a repeatable mechanism to cope with environmental stressors in a passerine bird
Bibliographic record
Abstract
Abstract For many vertebrates, urban environments are characterised by frequent environmental stressors. Coping with such stressors can demand that urban individuals activate energetically costly physiological pathways (e.g. the fight-or-flight response) more regularly than rural-living conspecifics. However, urban environments also commonly demand appreciable expenditure toward thermoregulation, owing to their often extreme climatic variations. To date, whether and how vertebrates can balance expenditure toward both the physiological stress response and thermoregulation, and thus persist in an urbanising world, remains an unanswered and urgent question among ecologists. In some species, changes in body surface temperature (T s ) and peripheral heat loss (q Tot ) that accompany the stress response are thought to balance energetic expenditure toward thermoregulation and responding to a stressor. Thus, augmentation of stressinduced thermal responses may be a mechanism by which urban individuals cope with simultaneously high thermoregulatory and stress-physiological demands. We tested whether stress-induced changes in T s and q Tot : (1) differed between urban- and rural-origin individuals, (2) reduce thermoregulatory demands in urban individuals relative to rural conspecifics, and (3) meet an essential first criterion for evolutionary responses to selection (variability among, and consistency within, individuals). Using the black-capped chickadee ( Poecile atricapillus ; n = 19), we show that neither rapid nor chronic changes in T s and q Tot following exposure to randomised stressors differed between urban- and rural-origin individuals (n urban = 9; n rural = 10). Nevertheless, we do find that stress-induced changes in T s and q Tot are highly repeatable across chronic time periods (R Ts = 0.61; R qTot = 0.67) and display signatures of stabilising or directional selection (i.e. reduced variability and increase repeatability relative to controls). Our findings suggest that, although urban individuals appear no more able to balance expenditure toward thermoregulation and the stress response than rural conspecifics, the capacity to do so may be subject to selection in some species. To our knowledge this is also the first study to report repeatability of any theorised stress-induced trade-off.
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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 | 0.000 |
| 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".