Intromittent Organ Morphology and Testis Size in Relation to Mating System in Waterfowl
Bibliographic record
Abstract
Abstract The waterfowl family Anatidae is one of very few avian taxa that possesses an intromittent organ. This paper examines the adaptive significance of the intromittent organ in waterfowl by determining the relationships between intromittent organ morphology and the intensity of sperm competition (as reflected by frequency of forced extrapair copulations [FEPCs]). Intromittent organ morphological characteristics, including length and circumference (adjusted for body size), number of ridges and knobs (per unit area), ridge or knob height, ridge or knob span, and area covered by ridges and knobs, were measured from scaled drawings of museum specimens of 54 waterfowl species (33 genera), 27 of which were ranked by frequency of FEPC (1 = monogamous, 2 = rare FEPC, 3 = frequent FEPC, and 4 = polygynous or promiscuous). Testes sizes were also investigated in relation to FEPCs, where testes mass (adjusted for body size) from 44 species (24 genera) were obtained (29 species with mating strategies). The size of the testes, the length of the intromittent organ, the height of the intromittent organ ridges and knobs, and the area covered by ridges and knobs increased significantly with the frequency of FEPC, and those relationships exist after correcting for common ancestry constraints. These results are consistent with the hypothesis that waterfowl intromittent organs are involved in sperm competition. Further research into the actual mechanism by which the intromittent organ is involved would be worthwhile.
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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 | 0.001 |
| 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) | 0.001 | 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".