A constellation of dysfunctional hybrid phenotypes enforces reproductive isolation between <i>Caenorhabditis</i> nematode species
Bibliographic record
Abstract
The evolution of complete reproductive isolation hinges on the cumulative action of reproductive isolating barriers that can manifest throughout the life cycle of an organism. Consequently, a comprehensive understanding of the features underlying the origin and maintenance of species requires assessing the relative contributions of distinct barriers to overall reproductive isolation. Here, we characterize multiple interrelated isolating barriers for the nematode sister species Caenorhabditis remanei and Caenorhabditis latens. We quantified F1 hybrid male sterility and characterized multiple phenotypic causes associated with developmental abnormalities in the germline as well as nongermline gonad and somatic tissues, uncovering a complex suite of developmental defects contributing to strong postzygotic reproductive isolation. Despite these multifarious isolating barrier traits, assays testing for interspecies sperm transfer under "choice" conditions did not yield evidence of premating isolation. In contrast to other Caenorhabditis species pairs, we also found no evidence that ectopic sperm migration acts as a postmating-prezygotic barrier. The constellation of phenotypic defects in hybrids points to a polygenic or highly pleiotropic basis for hybrid dysfunction and implicates more rapid evolution of intrinsic postzygotic reproductive isolation than prezygotic isolation in these organisms.
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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".