A molecular dissection of the mating system of the Dungeness crab, Metacarcinus magister (Brachyura: Cancridae)
Bibliographic record
Abstract
Microsatellites were used to determine paternity of Metacarcinus magister (Dana 1852), the Dungeness crab, embryos produced through controlled laboratory matings. Additionally, spermathecal and bursal sperm from mated females were genotyped to elucidate patterns of sperm storage and use. Spermathecal and bursal contents and egg clutches from female M. magister of unknown mating history were similarly analyzed. Genotyping of embryos revealed that bursal sperm are not used in fertilization. Multiple paternity was discovered in clutches from controlled matings and in 40% of clutches carried by crabs of unknown mating history. Males achieve last male sperm precedence through stratification of ejaculates within the spermatheca, but males may actually reduce their reproductive success by depositing too much sperm in the spermatheca. Stratification occasionally fails if the fresh ejaculate is large in volume, or when large volumes of stored sperm are present in the spermatheca, resulting in displacement of stored sperm towards the oviduct and multiple paternity within clutches. Sperm competition is interannual between the single primary male mate at each molt (adult females molt and mate once a year and sperm is retained across molts), and clutches fertilized with sperm as old as 2.5 years can develop to maturity. Female crabs may copulate for reasons other than to gain sperm for fertilization. Despite possessing internal sperm storage organs where oöcytes first encounter sperm, the act of fertilization in M. magister may occur externally.
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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) | 0.001 | 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".