Condition dependence of testis size in small mammals
Bibliographic record
Abstract
Sperm competition is a common phenomenon across the animal kingdom and is recognized as a major factor in the sexual selection of males. Intraspecific variation in testis size (ejaculate investment) has been implicated as an important factor in male reproductive success because larger testes produce higher quality ejaculates. Sexual selection theory predicts that traits associated with male–male competition or female mate choice must be costly and heritable to confer an evolutionary advantage to those individuals carrying such traits. Because ejaculate production can be costly, we tested the prediction that testis size is condition dependent using morphological data from three species of small mammals. In addition, subordinate males, which are less likely to copulate with a female at the optimal time for achieving fertilization, should invest more heavily in ejaculates than dominant males. Thus we also predicted that small males should invest more heavily in ejaculates than large males. In all three species, testis size was positively related to body condition (size-corrected body mass) and independent of body length. These results suggest that males in good condition are capable of investing more in ejaculates than males in poor condition, and are consistent with the costly nature of ejaculate production. In addition, the results are consistent with other traits that are condition dependent and that serve as honest signals of male quality, whether in the context of male–male competition or female mate choice.
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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 | 0.002 |
| 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) | 0.002 | 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".