Copulatory Fit of Common Bottlenose Dolphin ( <i>Tursiops truncatus</i> ) Genitalia
Bibliographic record
Abstract
Sexual selection is the primary force that drives gross morphological variation of male genitalia in many species. Less information is known about how male and female genitalia fit together during copulation or how sexual selection and mechanical constraints during copulation interact and shape reproductive organs. Marine mammals offer important insights into evolutionary forces that act on genital morphology in both sexes because of adaptations to extreme environmental constraints (e.g., hydrodynamic drag forces acting on the penis during copulation while swimming, the necessity to prevent seawater from entering the uterus, and the challenge of successful intromission while moving in a 3‐D space). Cetaceans (whales, dolphins, and porpoises) have a fibroelastic penis type and their vaginas have muscular folds, both characteristics that are rare among mammals and unique to cetartiodactlys. We used excised male and female reproductive tracts from deceased adult common bottlenose dolphins ( Tursiops truncatus ) to assess how deep the penis penetrates the vagina, which anatomical landmarks of male genitalia contact morphological features of females, and how genital shape influences copulatory interactions. Frozen‐thawed vaginas remained flaccid and were stained with iodine, while penises were mechanically inflated and formalin‐fixed to maintain rigidity. Female and male reproductive tracts were ct‐scanned independently. The penis was then inflated inside the vagina in a position that approximates real intromission and the reproductive tracts were ct‐scanned together. Resulting images were reconstructed in transverse and sagittal planes. In conjunction with video observations of copulations by free‐swimming dolphins, our results suggest that the tip of the bottlenose dolphin penis navigates around the female's single vaginal fold to achieve successful insemination. Understanding the coevolution of male and female reproductive anatomy under extreme environmental constraints has broad applications to conservation and captive breeding programs. Copulatory fit can provide clues of how genitals interact to influence fertility and improve artificial insemination techniques.
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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 | 0.000 | 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".