Size of brain, heart, liver, alimentary tract, and kidneys along altitudinal gradients in Asiatic toad
Bibliographic record
Abstract
Brain size variation is frequently linked to energetic trade-offs with other metabolically demanding tissues or organs, a concept central to the expensive brain hypothesis (EBH). In this study, we investigate Asiatic toads (Bufo gargarizans) along altitudinal gradients, focusing on the trade-offs in size between the brain and four key visceral organs: the heart, liver, alimentary tract, and kidney. We estimated brain volume by measurement. We measured the dry weight of four organs: the heart, liver, alimentary tract, and kidneys. Additionally, we measured the snout-vent length and body weight of individuals. Our results indicate that both body size and scaled mass index—an indicator of total energy intake—decrease at higher altitudes, suggesting increased energetic constraints in high altitudinal environments. As altitude rises, we observe a reduction in relative brain size, while the relative sizes of visceral organs tend to increase. Through structural equation modeling, we identify a significant negative correlation between brain size and a latent variable termed "budget," which reflects energy allocation to the four visceral organs in high-altitude toads. Notably, the heart shows the most pronounced and consistent response to variations in energy distribution. In contrast, no such relationships are observed in toads at mid- and low-altitudes, where higher energy intake may enable individuals to bypass these trade-offs. When considering EBH in poikilothermic species, it is essential to emphasize total energy intake alongside energy allocation strategies. Future research on EBH should focus on intra-specific comparisons and explore the fitness implications that extend beyond mere energy constraints.
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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 | 0.001 | 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 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".