Direct and indirect fitness effects of plant metabolites and genetic constraints limit evolution of allelopathy in an invading plant
Bibliographic record
Abstract
Abstract Invading species encounter novel communities of consumers, pathogens, and competitors. Both phenotypic plasticity and rapid evolution can facilitate invasion across these heterogenous communities. However, the rate and extent of adaptive evolution on contemporary timescales can be constrained by adaptive phenotypic plasticity and the genetic architecture of traits under selection. We measured phenotypic plasticity and quantified genetic variation for growth, leaf chlorophyll a (Chl a ) and glucosinolates, and lifetime fitness among 23 naturally inbred seed families of Alliaria petiolata (garlic mustard) collected across its invasive range in eastern North America. After growing a self-pollinated generation in a uniform common garden to reduce maternal effects, we reared second-generation plants in a two-year greenhouse and field experiment with naïve soil from an uninvaded habitat. We estimated selection gradients and causal factors affecting lifetime fitness when reared alone, with an intraspecific competitor, and under interspecific competition with naïve Acer saccharum (sugar maple) saplings. We defined Total Metabolite Production (TMP) as the first principal component of Chl a and glucosinolate concentrations, accounting for 84% of variation in these two traits. TMP was significantly plastic across growing environments ( p < 0.001) with limited broad-sense heritability ( H 2 = 2.91; p = 0.08). Path analysis revealed that plastic phenotypes with higher TMP had an indirect positive effect on A. petiolata fitness via a direct, negative effect on performance of A. saccharum competitors. In contrast, the second principal component defined Relative Glucosinolate Investment (RGI), which was significantly heritable ( H 2 = 16.91, p < 0.001) with no detectable plasticity across treatments. Variation in RGI among A. petiolata genotypes had a direct, positive effect on A. saccharum performance and an indirect negative effect on A. petiolata fitness. Synthesis. Adaptive evolution of allelopathy during invasion has been constrained by (i) a lack of heritable genetic variation for allelopathy, (ii) high plasticity for TMP across competition treatments, and (iii) selection for lower RGI under interspecific and intraspecific competition. As an alternative to eco-evolutionary feedbacks, plasticity in TMP may be an overlooked explanation for variable performance of A. petiolata across its introduced range.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".