Multiple sperm storage organs facilitate female control of paternity
Bibliographic record
Abstract
It has been proposed that multiple sperm storage organs (spermathecae) could allow polyandrous females to control paternity. There is little conclusive evidence for this since insemination of individual spermathecae is generally not experimentally manipulable. Here, we examined sperm use patterns in the Australian redback spider (Latrodectus hasselti), which has paired, independent spermathecae. We assessed paternity when two rivals were forced to inseminate a single storage organ or opposite storage organs. When males inseminated a single spermatheca, mean paternity of the female's first mate was 79.8% (median 89.4%), and 38% of first mates achieved 100% paternity. In contrast, when males inseminated opposite organs, the mean paternity of the first mate was 49.3% (median 49.9%), only 10% of males achieved complete precedence, and paternity was normally distributed, suggesting sperm mixing. Males responded to this difference by avoiding previously inseminated female reproductive tracts. Complete sperm precedence can only be achieved if females permit males to copulate with both reproductive tracts. Females often cannibalize smaller males during their first copulation, thus limiting their paternity to 50%. These data show that multiple sperm storage organs can increase female control of paternity.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".