Ecological mechanisms of reproductive isolation between diploid and tetraploid <i>Chamerion angustifolium</i>
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Bibliographic record
Abstract
Summary 1 Theoretical models indicate that coexistence of diploid and polyploid individuals in sympatric populations is unlikely when mating is random among cytotypes and hybrids are inviable. However, coexistence may be facilitated by prezygotic isolating mechanisms that reduce intercytotype mating and increase assortative mating. 2 We examined the ecological factors regulating intercytotype mating in Chamerion (formerly Epilobium ) angustifolium by measuring floral morphology, flowering synchrony and insect foraging preferences in a mixed population within a diploid–tetraploid contact zone. We also calculated the minimum rate of between‐cytotype mating from estimates of the frequency of triploid offspring. 3 Diploids had significantly shorter and narrower petals as well as shorter styles than tetraploids. Inflorescences were significantly taller in tetraploids than diploids, but the mean number of open flowers per inflorescence did not differ. Diploid and tetraploid flowering periods overlapped by 51%, with diploid stems flowering earlier. 4 In a plot of 20 diploid and 28 tetraploid stems that were flowering simultaneously, only 26% of all bee flights were between flowers on different stems. Of the total flights between inflorescences, only 15% were between different cytotypes. The combined effects of flowering asynchrony and insect foraging reduced the opportunities for intercytotype mating from 49% expected if mating is random to about 2% of the total number of pollinator flights. 5 A computer simulation indicated that the deficiency of pollinator flights between cytotypes was due largely to the spatial structure of cytotypes and limited pollinator flight distances within the observation plot. The frequency of triploid offspring produced during the period when both cytotypes were in flower was 6.6%, similar to the proportion of flights observed between flowers on different cytotypes (4%). 6 The results indicate that flowering phenology and insect behaviour (as influenced by clonal structure) have a significant effect on prezygotic mating isolation and triploid production, and may contribute to the maintenance of mixed cytotype populations in Chamerion angustifolium .
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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 it