Comparative Chloroplast Genomes to Gain Insights into the Phylogenetic Relationships and Evolution of Opisthopappus Species
Bibliographic record
Abstract
The investigation and comparison of chloroplast genomes facilitate our deeper elucidation of the evolutionary dynamics and phylogenetics of plant species, particularly non-model plants. Opisthopappus is a genus of Asteraceae that is endemic to the Taihang Mountains in China, which includes Opisthopappus taihangensis and Opisthopappus longilobus. Although certain chloroplast genomic data are available, the comprehensive evolutionary relationships of chloroplast genomes in this genus are not yet fully understood. In this study, the assembled O. taihangensis chloroplast genomes exhibited a quadripartite structure with 131 genes, encompassing 86 protein-coding, 37 tRNA, and eight rRNA genes. The basic phylogenetic relationships of 275 Asteraceae species were consistent with preceding studies. Opisthopappus with Ajania and Chrysanthemum were gathered together in Trib. Anthemideae. However, O. taihangensis and O. longilobus were not clustered into a group. Six and eight variable hotspots were detected in Opisthopappus and Asteraceae respectively. A total of 18 optimal codons were identified in two species. Differentiation in codon usage patterns was primarily influenced by natural selection between O. taihangensis and O. longilobus. Thereinto, GCU (Ala) was specific to O. taihangensis, while ACU (Thr) was to O. longilobus. Most of the codons preferentially ended with A/U, with only two genes (rpl16 and matK) being subjected to positive selection in Opisthopappus. Under salt stress, 25 editing sites were detected in O. longilobus, and 34 editing sites were found in O. taihangensis. All editing sites were C to U transitions. Distinct editing events occurred in the two species. During the evolution of chloroplast genomes, the genes that undergo positive selection may help two Opisthopappus species to adapt the harsh cliff environment of the Taihang Mountains and ensure their normal growth and development. In response to stress, O. taihangensis and O. longilobus tended to utilize different codons and initiate unique RNA editing events. These will facilitate further work on taxonomy, phylogenetics, and adaptive evolution of Opisthopappus, even Anthemideae or Asteraceae.
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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 | 0.001 |
| 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) | 0.001 | 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".