Gape and energy limitation determine a humped relationship between trophic position and body size
Bibliographic record
Abstract
We found a segmented pattern, increasing for small sizes and decreasing for larger sizes, in the relationship between trophic position and body size. This pattern provides support for a recently developed theoretical model whose derivation was based on consumers’ metabolic requirements and on basic assumptions about feeding relationships. We combined original and published information about stable nitrogen isotopes, a proxy of trophic position, for a broad range of animal body sizes (10 −3 –10 5 kg) inhabiting the southwestern Atlantic Ocean. Linear, polynomic, and piecewise segmented models were fit to species trophic position and body mass. The segmented model had the best fit, presenting a positive slope (β 1 = 0.33 ± 0.08) for small organisms (<200 kg) and a negative slope (β 2 = −1.93 ± 0.16) for larger ones. This suggests that there are morphological restrictions to prey consumption in smaller organisms and energetic constraints to trophic position in larger ones. Furthermore, the predator–prey body mass ratio (BMR = 1.31; 95% CI = 0.9–2.40) estimated here is similar to previous reports of direct observations (BMR = 1.64 and 1.82). However, the trophic position of larger organisms decreases at a faster rate (β 2 = −1.93) than expected by metabolic demand (β 2expected = −0.16 to −0.82), suggesting that additional processes should be considered. Our results suggest that large species could be more vulnerable to global change than previously thought.
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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 | 0.001 | 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".