Testing for Differences in Metabolism Among Females and Dimorphic Males of Four Dung Beetle Species (Coloeoptera: Scarabaeinae)
Bibliographic record
Abstract
Synopsis Both sexual and male dimorphism are common in nature, yet we have limited understanding of how different developmental pathways and reproductive strategies of morphs shape energetics. To address this gap, we examined metabolic rates of four species of dung beetle (Onthophagus taurus, Onthophagus hecate, Oxysternon silenus, and Phanaeus vindex) with both sexual and male dimorphism. In these species, males have horn length dimorphism, including larger-horned (“major”) males and smaller-horned (“minor”) males. The gene doublesex, dsx, drives both sexual dimorphism and, by mediating nutrition-dependent horn growth in some species, male dimorphism. Because females and minor males share developmental pathways and have greater investment in reproductive organs than major males, we hypothesized energetic costs would be similar and higher in females and minor males compared to major males. To test this hypothesis, we examined metabolic rates of morphs using flow-through respirometry to record CO2 output. After accounting for body size and activity level, we found that in two species, Onthophagus taurus and Phanaeus vindex, females had higher CO2 production compared to major males, and in O. taurus, females also had higher CO2 production than minor males. We detected no differences between sexes for O. hecate and O. silenus. We also found no significant difference in metabolic rates between major and minor males of any species. Our results suggest that, for these species of dung beetles, any energetic tradeoffs due to reproductive strategies occur between females and males, but not between male morphs. The lack of a general trend in metabolic rates suggests energetic costs are decoupled from sex and male morph across dung beetle species, which runs counter to evolutionary explanations for the maintenance of alternative reproductive tactics.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".