Selfing results in inbreeding depression of growth but not of gas exchange of surviving adult black spruce trees
Bibliographic record
Abstract
In most tree species, inbreeding greatly reduces seed production, seed viability, survival and growth. In a previous large-scale quantitative analysis of a black spruce (Picea mariana (Mill.) B.S.P.) diallel experiment, selfing had large deleterious effects on growth but no impact on stable carbon isotope discrimination (an indirect measure of the ratio of net photosynthesis (A) to stomatal conductance (gwv)). It was hypothesized that selfing has no effect on carbon (C) fixation at the leaf level but impairs subsequent utilization of C. Alternatively, A and gwv may be impacted by selfing to the same extent. However, no gas exchange data were collected to test these hypotheses. We have now obtained photosynthetic gas exchange data from three selfed families and three outcrossed families (all the result of controlled pollination) from the same diallel experiment. Photosynthetic responses to intercellular CO2 concentration (A-Ci curves) were generated on four replicates per family, one block per day, over a 4-day period in July. There were no differences between selfed and outcrossed families in maximum carboxylation rate, maximum electron transport, A or gwv (both estimated at 370 ppm CO2), or the ratio A/gwv. Because selfed trees had higher mortality than outcrossed trees during the experiment, we cannot exclude the possibility that previously living selfed progeny had low A. Nevertheless, the data indicate that inbreeding can result in trees that have low productivity despite high A, supporting our hypothesis that gas exchange is similar between selfed and outcrossed progeny trees. We conclude that utilization of fixed C is modified in the surviving selfed progeny.
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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 | 0.000 |
| 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 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".