One function of sex — an empirical study of genetic and ecological variation
Bibliographic record
Abstract
Abstract The question “why sex?” is a longstanding fundamental puzzle in biology. Although there may be several answers, no satisfactory theory has emerged. We present an argument in favour of one function of sex, derived from a study of the population genetics and ecology of the cabbage butterfly,Pieris rapae(L.) (Lepidoptera: Pieridae), on three continents between 1984 and 2009, and from previously published studies of other organisms. We provide evidence that responsiveness to directional selection (RDS), a measure related to “narrow-sense heritability”, can be dramatically reduced by truncation selection in a single generation and rapidly restored within a few generations. Viewing a population as a collection of sexual families, we show that rapid restoration of RDS after truncation selection is essential to maintain population variance. The only known mechanism that will rapidly restore RDS is sexual recombination. We therefore conclude that inP. rapae, sex restores the genetic variation that a population needs to match unpredictable environmental variation, despite selection tending to reduce that genetic variation.
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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 | 0.003 | 0.016 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".