Beyond pollen:ovule ratios: Evolutionary consequences of pollinator dependence and pollination efficiency for pollen and ovule production in angiosperms
Bibliographic record
Abstract
PREMISE: The relative per-flower production of ovules and pollen varies broadly with angiosperm mating systems, with outcrossing types commonly producing more pollen grains per ovule than selfing types. The evolutionary causes of this variation are contentious, especially the relevance of pollination risk. Resolution of this debate may have been hampered by its focus on pollen:ovule (P:O) ratios rather than on the evolution of pollen and ovule numbers per se. METHODS: Using published mean ovule and pollen counts, we analyzed associations with the proportion of removed pollen that reaches stigmas (pollen-transfer efficiency) and differences between pollinator-dependent and autogamous forms within and among species. Analyses involved Bayesian methods that simultaneously considered variation in pollen and ovule numbers and accounted for phylogenetic relatedness. We also assessed the utility of P:O ratios as mating-system proxies and their association with female outcrossing rates. RESULTS: Median pollen number declined consistently with pollen-transfer efficiency among species, whereas median ovule number did not. Similarly, in both intraspecific and interspecific analyses, pollinator-dependent plants produced more pollen than autogamous plants, whereas ovule production did not differ statistically. Distributions of P:O ratios overlapped extensively for self-incompatible and self-compatible species and for different mating-system classes, and P:O ratios correlated weakly with outcrossing rate. CONCLUSIONS: Our findings demonstrate that pollinator dependence and pollination efficiency commonly influence the evolution of pollen number per flower but have more limited effects on ovule number. P:O ratios provide ambiguous, possibly misleading, information about mating systems, especially when compared among clades.
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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 | 0.001 |
| 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".