Convergent Plastome Evolution and Gene Loss in Holoparasitic Lennoaceae
Bibliographic record
Abstract
The Lennoaceae, a small monophyletic plant family of root parasites endemic to the Americas, are one of the last remaining independently evolved lineages of parasitic angiosperms lacking a published plastome. In this study, we present the assembled and annotated plastomes of two species spanning the crown node of Lennoaceae, Lennoa madreporoides and Pholisma arenarium, as well as their close autotrophic relative from the sister family Ehretiaceae, Tiquilia plicata. We find that the plastomes of L. madreporoides and P. arenarium are similar in size and gene content, and substantially reduced compared to T. plicata, consistent with trends seen in other holoparasitic lineages. In particular, most plastid genes involved in photosynthesis function have been lost, whereas housekeeping genes (ribosomal protein-coding genes, rRNAs, and tRNAs) are retained. One notable exception is the persistence of a rbcL open reading frame in P. arenarium but not L. madreporoides suggesting a nonphotosynthetic function for this gene. Of the retained coding genes, dN/dS ratios indicate that some remain under purifying selection, whereas others show relaxed selection. Overall, this study supports the mounting evidence for convergent plastome evolution in flowering plants following the shift to heterotrophy.
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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 | 0.001 | 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) | 0.001 | 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".