Pattern of sperm transfer in redback spiders: implications for sperm competition and male sacrifice
Bibliographic record
Abstract
Many sperm competition studies have identified copulation duration as an important predictor of paternity. This result is often interpreted as a sperm transfer effect--it is assumed that sperm transfer is limited by copulation duration. Here we test the assumption of duration-dependent sperm transfer in the Australian redback spider, Latrodectus hasselti, in which a correlation between copulation duration and paternity has been implicated in the evolution of a rare male self-sacrifice behavior. Male redbacks facilitate sexual cannibalism by females during copulation. Sexual cannibalism is apparently adaptive for redback males, in part because it results in longer copulations (25 versus 11 min.), and copulation duration is positively correlated with paternity. We assessed sperm transfer in normal copulations and in copulations that we terminated at 5, 10, or 20 min. Our results show that the paternity advantage of sexual cannibalism is not owing to time-dependent sperm transfer, as redback males transfer the majority of their sperm within the first 5 min of copulation. This suggests that the link between copulation duration and paternity may instead be owing to cryptic female choice or the transfer of nongametic ejaculatory substances. Results further indicate that the act of cannibalism itself might play a role in mediating sperm transfer. This study highlights the importance of understanding mechanisms of sperm transfer when attempting to interpret the outcome of sperm competition studies. Copyright 2004.
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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 | 0.001 | 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".