Natural hybridization between Dall's porpoises (<i>Phocoenoides dalli</i>) and harbour porpoises (<i>Phocoena phocoena</i>)
Bibliographic record
Abstract
Natural hybridization occurs rarely in mammals compared with other taxonomic groups of animals. Cetaceans appear unique among mammals in exhibiting striking karyological uniformity, which suggests that they have the potential to produce hybrid offspring more readily than other mammals. However, the detection and accurate identification of wild mammalian hybrids is difficult, and molecular evidence for wild cetacean hybrids is extremely limited. Here, we present molecular and morphological evidence of frequent hybridization between free-ranging Dall's, Phocoenoides dalli (True, 1885), and harbour, Phocoena phocoena (L., 1758), porpoises. The study describes a temporally and geographically concentrated case of natural hybridization in large mammals. Molecular analyses of mitochondrial and nuclear DNA revealed the species identity, sex, and direction of cross of several hybrid individuals. In concert with morphological and behavioural observations, these data confirmed the hybrid status of putative crosses in the field, including reproductive females. All crosses examined had Dall's porpoise as the maternal parent. This directionality may reflect the indiscriminate pursuit of female porpoises by male harbour porpoises. Our finding of extensive localized hybridization, despite apparently strong isolation elsewhere in their range, suggests that ecological influences on mating behaviour may be of primary importance in the reproductive isolation of these, and possibly other, cetacean species.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".