The Chloroplast Genome Sequence of <i>Chlorokybus Atmophyticus</i>: Evidence that Charophycean Green Algae from an Early Diverging Lineage Adapted to Terrestrial Life
Bibliographic record
Abstract
Abstract Land plants and green algae belonging to the Charophyceae sensu Mattox and Stewart form the Streptophyta, a lineage sister to the Chlorophyta which comprises most or all of the other green algae. A third green plant lineage, at the base of the split of the Chlorophyta and Streptophyta, is possibly represented by the green alga Mesostigma viride; however, this remains controversial because some phylogenetic analyses place Mesostigma within the Streptophyta. Five orders have been recognized in the Charophyceae: the Chlorokybales, Klebsormidiales, Zygnematales, Coleochaetales, and Charales. Based on its sarcinoid thallus, the only species in the Chlorokybales, Chlorokybus atmophyticus, has long been regarded as the earliest‐diverging member of the Charophyceae. This rare species has been collected only in terrestrial habitats. In the present study, we have determined the complete chloroplast DNA (cpDNA) sequence (149 681 bp) of Chlorokybus to gain insight into its phylogenetic position and also to better understand how the chloroplast genome evolved in the Streptophyta. We have found that Chlorokybus cpDNA closely resembles Mesostigma cpDNA in showing a high degree of ancestral features. It displays a quadripartite structure, encodes 138 genes (only two extra genes compared to Mesostigma cpDNA), and contains a single intron (in trnL(UAA)). The gene order in Chlorokybus cpDNA is similar to that of Mesostigma cpDNA; we estimate that 14 inversions would be required to convert the gene order of one alga into that of the other. Phylogenetic analyses of combined chloroplast protein sequences from Mesostigma, Chlorokybus, other streptophytes, and a number of chlorophytes will be presented. Overall, our results support the idea that the Chlorokybales represent an early diverging lineage.
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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) | 0.001 | 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".