Recombination in a natural population of the bdelloid rotifer <i>Adineta vaga</i>
Bibliographic record
Abstract
Sexual reproduction which involves alternation of meiosis and syngamy is the ancestral condition of extant eukaryotes. Transitions to asexual reproduction were numerous, but most of the resulting eukaryotic lineages are rather short-lived. Still, there are several exceptions to this rule including darwinulid ostracods 1,2 and timema stick insects 3 . The most striking of them is bdelloid rotifers 4 – 6 , microscopic freshwater invertebrates which underwent an extensive adaptive radiation after apparently losing meiosis over 10 Mya. Indeed, both the lack of males in numerous bdelloid species and the lack of proper homology between chromosomes 6 rule out ordinary sex. However, this does not exclude the possibility of some other mode of interindividual genetic exchange and recombination in their populations 7 . Recent analyses based on a few loci suggested genetic exchanges in this group 8,9 , although this has been controversial 10 . Here, we compare complete genomes of 11 individuals from the wild population of the bdelloid rotifer Adineta vaga, and show that its genetic structure, which involves Hardy-Weinberg proportions of genotypes within loci and lack of linkage disequilibrium between distant loci, is incompatible with strictly clonal reproduction. Instead, it can emerge only under ongoing recombination between different individuals within this species, possibly through transformation. Such a genetic structure makes the population immune to negative long-term consequences of the loss of conventional meiosis 11 , although this does not necessarily imply that interindividual genetic exchanges in A. vaga are directly maintained by natural selection.
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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 | 0.001 | 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".