Origin and maintenance of sex: the evolutionary joys of self sex
Bibliographic record
Abstract
Sex is generally thought of as meiosis, conjugation, and syngamy, with the primary function of sex believed to be genetic mixing. However, conjugation does not occur with complete automixis, whereas syngamy does not occur with restitutional automixis. Self sex in the forms of automixis and autogamy does not include genetic mixing. Yet sex, including self sex, is necessary for most eukaryotic lineages. What is the purpose of sex without genetic mixing? Obligate self sex is not an evolutionary dead end, but holds the key to understanding the evolutionary origin, function, maintenance, and ubiquity of sex. We extend the rejuvenescence hypothesis that sex provides a necessary developmental reset for multicellular eukaryotes and even many unicellular eukaryotes. Sex reduces additive genetic variance of epigenetic signals, especially cytosine methylation, and of ploidy levels. Furthermore, we argue that syngamy is a modified form of meiosis that maintains ploidy and resets epigenetic signals. Epigenetic resetting is consistent with sex being induced by starvation or desiccation. Diminution of additive genetic variance is consistent with the origin and maintenance of an adaptive trait, sex, that has been present for approximately two billion years. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 707‐728.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".