How evolution repeatedly builds complexity: a case study with <scp>C<sub>4</sub></scp> photosynthesis in <i>Blepharis</i> (Acanthaceae)
Bibliographic record
Abstract
Summary With over 60 parallel origins representing evolutionary replicates, C 4 photosynthesis is well‐suited for studying complex trait evolution. However, lineages with diverse C 3 –C 4 intermediate species are scarce, leaving uncertainty in models of C 4 evolution. Phenotypic characterization of 28 living species of Blepharis (Acanthaceae) is presented, including photosynthetic gas exchange, enzyme activity assays, cell ultrastructure, and δ 13 C assays, the latter including 92 herbarium specimens from three species with phenotypic diversity. A well‐resolved transcriptome‐based phylogeny provides evolutionary context. C 3 , proto‐Kranz, C 2 , C 4 ‐like, and C 4 phenotypes occur in Blepharis sect. Acanthodium . The phylogeny supports a stepwise progression from C 3 through C 2 to C 4 states and up to five distinct origins of the C 4 cycle. Substantial intraspecific C 2 –C 4 variation is demonstrated in Blepharis mitrata , Blepharis furcata , and Blepharis macra . Blepharis gazensis is a monospecific C 4 lineage exhibiting an NADP malic enzyme C 4 pathway with features of the NAD‐ME subtype, extending the ways in which the C 4 cycle is known to function. Substantial photosynthetic diversity exists in Blepharis that rivals or exceeds the range of character states present in other C 3 to C 4 transitional lineages. This diversity in Blepharis represents a robust new model for studying convergent evolution of C 4 photosynthesis and complex traits in general.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".