Ageing gracefully: physiology but not behaviour declines with age in a diving seabird
Why this work is in the frame
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Bibliographic record
Abstract
Summary A higher proportion of long‐lived animals die from senescence than short‐lived animals, yet many long‐lived homeotherms show few signs of physiological ageing in the wild. This may, however, differ in long‐lived diving homeotherms that frequently encounter hypoxic conditions and have very high metabolic rates. To examine ageing within a long‐lived diving homeotherm, we studied resting metabolism and thyroid hormones ( N = 43), blood oxygen stores ( N = 93) and foraging behaviour ( N = 230) of thick‐billed murres ( U ria lomvia ). Because murres dive exceptionally deep for their size and have a very high metabolism, we expected that ageing murres would show signs of physiological senescence. We paid particular attention to resting metabolism as we argue that these maintenance costs reflect those experienced during deep dives. Blood oxygen stores (haematocrit), resting metabolic rate and thyroid hormone levels all declined significantly with age in incubating murres 3–30 years of age. In birds measured longitudinally 3 years apart, thyroid hormone levels and haematocrit were both significantly lower, suggesting progressive changes within individuals rather than selective disappearance of individuals with high metabolic rates. Within our longitudinal data set, we found no effect of age on dive depth, dive shape or behavioural aerobic dive limit. A meta‐analysis of changes in resting metabolism with age across 15 animal species demonstrated that such declines are pervasive across most of the kingdom. The rate of decline was highest in species with high energy expenditure supporting a linkage between metabolism and senescence. Physiological changes occurred in tandem with advancing age in murres, but offset each other such that there was no detectable decline in behavioural performance.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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 it