HIGH FIDELITY OF MITOCHONDRIAL GENOME TRANSMISSION UNDER THE DOUBLY UNIPARENTAL MODE OF INHERITANCE IN FRESHWATER MUSSELS (BIVALVIA: UNIONOIDEA)
Bibliographic record
Abstract
Doubly uniparental inheritance (DUI) of mitochondrial DNA (mtDNA) has been demonstrated in both mytilid and unionid bivalves. Under DUI, females pass on their mtDNA to both sons and daughters, whereas males pass on their mtDNA to only sons. In mytilids, the loss of an original male (or M) mitotype, with its subsequent replacement by that lineage's female (or F) mitotype, has been called a role-reversal or, more specifically, a masculinization event. Multiple masculinization events have been inferred during the evolutionary history of mytilids but not unionids. The perceived lack of role-reversal events in unionids may represent a significant difference in the evolutionary dynamics of DUI between the two bivalve taxa or simply a lack of sufficient taxon sampling in unionids. To evaluate these alternative hypotheses, six additional unionoidean bivalve genera were sampled for DUI including one genus from the sister taxon of the Unionidae, the Hyriidae. Phylogenetic analyses of 619 base pairs of cytochrome c oxidase I (COI) from eight genera (nine species) of unionoidean bivalves, plus the sister taxon to the Unionoida, Neotrigonia, revealed that the M and F unionoidean mitotypes were contained in gender-specific, topologically congruent clades. This supports the hypothesis that either role-reversal events do not occur in unionoideans or, if they do occur, their products are ephemeral in an evolutionary sense. Furthermore, the fact that the mantle-tissue-derived Neotrigonia mitotype is the sister mitotype to the unionoidean F mitotype clade suggests that DUI has been operating with high fidelity in unionoids for at least 200 million years. A relatively low incidence of interspecific hybridization in unionoideans and a possibly obligate role for the M mitotype in unionoidean gender determination are offered as potential explanations for the disparate evolutionary dynamics of DUI observed between mytilid and unionoidean bivalves.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".