Experimental manipulation of flowers to determine the functional modes and fitness consequences of self‐fertilization: unexpected outcome reveals key assumptions
Bibliographic record
Abstract
Summary Reproductive assurance is often invoked to explain the repeated transition from outcrossing to selfing among plants. The most common experimental test of this hypothesis uses floral emasculation (anther removal) to manipulate the capacity of flowers for autogamous self‐pollination. The coastal dune endemicCamissoniopsis cheiranthifoliaexhibits striking variation in floral morphology and the mating system across its geographic range inCalifornia, and reproductive assurance is likely to have played a role in the transition from large flowers and predominant outcrossing to small flowers and predominant selfing. To compare variation in the timing of self‐pollination and the extent to which it provides reproductive assurance in large‐ vs. small‐flowered populations, we emasculated flowers at different times during anthesis and measured the effects on both seed production and the proportion of seeds self‐fertilized vs. outcrossed estimated using marker genes. We also manipulated large‐ vs. small‐flowered phenotypes within two morphologically variable populations. As predicted from floral development, small‐flowered plants self‐pollinated before flowers open, whereas large‐flowered phenotypes did not. Comparing flowers that were emasculated before closing suggested that a seemingly well‐developed mechanism for delayed selfing (anthers contacting the stigma when flowers close) does not increase seed production. Using emasculation to manipulate selfing assumes that removing anthers from flowers does not compromise outcrossing. However, while not affecting the capacity of flowers to produce seed, emasculation shortened floral longevity, thereby reducing opportunities for outcrossing. Genetic estimation of the mating system revealed a negative effect of emasculation on the proportion of seed outcrossed, even in small‐flowered populations, further suggesting that flowers lacking anthers are unattractive to pollinators. These side effects of emasculation prevent a clear interpretation of the reproductive assurance value of selfing. Given that much of what we know about reproductive assurance in natural populations comes from emasculation experiments, our results suggest that the assumptions of this approach, which are rarely verified, require much more serious consideration.
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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 | 0.001 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".